Definitions - Glossary K thru O
This is a central location for the definitions available for many of the technical or medical words found on this site. Please click on the letters below to find definitions for words starting with that letter.
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Special thanks to the National Cancer Institute (NCI). Many of the definitions in this glossary were adapted or taken directly from the NCI's Dictionary of Cancer Terms.

ABCDEFGHIJKLMNOPQRSTUVWXYZ

Kahler's disease
A type of cancer that begins in plasma cells (white blood cells that produce antibodies). Also called multiple myeloma, myelomatosis, or plasma cell myeloma.

Kaposi's sarcoma (KAP-o-seez sar-KO-ma)
A type of cancer characterized by the abnormal growth of blood vessels that develop into skin lesions or occur internally.

Kaposi's sarcoma-associated herpesvirus
KSHV. A type of herpesvirus that may cause Kaposi's sarcoma (a rare cancer that can cause skin lesions) and a type of lymphoma (cancer that begins in the lymph system), especially in patients who have a weak immune system. Also called human herpesvirus 8 (HHV8).

karenitecin
A drug being studied in the treatment of cancer. It belongs to a family of drugs called topoisomerase inhibitors. It is related to the anticancer drug camptothecin.

Karnofsky Performance Status
KPS. A standard way of measuring the ability of cancer patients to perform ordinary tasks. The Karnofsky Performance scores range from 0 to 100. A higher score means the patient is better able to carry out daily activities. KPS may be used to determine a patient's prognosis, to measure changes in a patient's ability to function, or to decide if a patient could be included in a clinical trial.

kava kava (KAH-vuh KAH-vuh)
An herb native to islands in the South Pacific. Substances taken from the root have been used in some cultures to relieve stress, anxiety, tension, sleeplessness, and problems of menopause. Kava kava may increase the effect of alcohol and of certain drugs used to treat anxiety and depression. The U.S. Food and Drug Administration advises users that kava kava may cause severe liver damage. Also called intoxicating pepper, rauschpfeffer, tonga, and yangona. The scientific name is Piper methysticum.

keloid (KEY-loyd)
A thick, irregular scar caused by excessive tissue growth at the site of an incision or wound.

kelp
Laminaria digitata. A type of seaweed. The stem-like parts of this plant have been used in some cultures to treat certain medical problems. It may have immunostimulatory and anticancer effects.

Kepivance
A form of keratinocyte growth factor (KGF) that is made in the laboratory. KGF stimulates the growth of cells that line the surface of the mouth and intestinal tract. Kepivance is used to prevent and treat oral mucositis (mouth sores) caused by high-dose chemotherapy and radiation therapy in leukemia and lymphoma. It is also being studied in the prevention and treatment of oral mucositis (mouth sores) and dysphagia (difficulty swallowing) in other types of cancer. Kepivance belongs to the family of drugs called recombinant human keratinocyte growth factors. Also called palifermin.

keratan sulfate
A glycosaminoglycan (a type of polysaccharide) found in cartilage and in the cornea of the eye.

keratinocyte growth factor
KGF. A substance that stimulates the growth of epithelial cells that line the surface of the mouth and intestinal tract. There are several forms of KGF. Recombinant human KGF (rHuKGF) is being studied in the prevention of graft-versus-host disease (GVHD) that may occur after tissue transplantation, and in the treatment of mucositis caused by chemotherapy and radiation therapy. rHuKGF is also called palifermin.

keratoacanthoma (KER-a-toe-AK-an-THOW-ma)
A benign (noncancerous), rapidly growing skin tumor that usually occurs on sun-exposed areas of the skin and that can go away without treatment.

ketoconazole (kee-ta-KOE-na-zol)
A drug that treats infection caused by a fungus. It is also used as a treatment for prostate cancer because it can block the production of male sex hormones.

ketone (KEE-tone)
A type of chemical substance used in perfumes, paints, solvents, and found in essential oils (scented liquid taken from plants). Ketones are also made by the body when there is not enough insulin.

ketorolac
A drug that belongs to a family of drugs called nonsteroidal anti-inflammatory agents. It is being studied in cancer prevention.

keyhole limpet hemocyanin
KLH. One of a group of drugs called immune modulators, given as a vaccine to help the body respond to cancer.

KGF
Keratinocyte growth factor. A substance that stimulates the growth of epithelial cells that line the surface of the mouth and intestinal tract. There are several forms of KGF. Recombinant human KGF (rHuKGF) is being studied in the prevention of graft-versus-host disease (GVHD) that may occur after tissue transplantation, and in the treatment of mucositis caused by chemotherapy and radiation therapy. rHuKGF is also called palifermin.

kidney (KID-nee)
One of a pair of organs in the abdomen. Kidneys remove waste from the blood (as urine), produce erythropoietin (a substance that stimulates red blood cell production), and play a role in blood pressure regulation.

kidney cancer (KID-nee KAN-ser)
Cancer that forms in tissues of the kidneys. Kidney cancer includes renal cell carcinoma (cancer that forms in the lining of very small tubes in the kidney that filter the blood and remove waste products) and renal pelvis carcinoma (cancer that forms in the center of the kidney where urine collects). It also includes Wilms' tumor, which is a type of kidney cancer that usually develops in children under the age of 5.

kidney failure (KID-nee FAYL-yer)
A condition in which the kidneys stop working and are not able to remove waste and extra water from the blood or keep body chemicals in balance. Acute or severe kidney failure happens suddenly (for example, after an injury) and may be treated and cured. Chronic kidney failure develops over many years, may be caused by conditions like high blood pressure or diabetes, and cannot be cured. Chronic kidney failure may lead to total and long-lasting kidney failure, called end-stage renal disease (ESRD). A person in ESRD needs dialysis (the process of cleaning the blood by passing it through a membrane or filter) or a kidney transplant. Also called renal failure.

killer cell
A white blood cell that attacks tumor cells and body cells that have been invaded by foreign substances.

kilogram
A measure of weight. A kilogram is equal to 2.2 pounds.

Kinaret
A substance that is used to treat rheumatoid arthritis, and is being studied in the treatment of cancer. Kinaret blocks the action of interleukin 1 (IL-1). It belongs to the family of drugs called interleukin receptor antagonists. Also called anakinra.

Klatskin tumor
Cancer that develops in cells that line the bile ducts in the liver, where the right and left ducts meet. It is a type of cholangiocarcinoma.

Klebsiella
A bacteria that frequently causes lung, urinary tract, intestinal, and wound infections.

Klinefelter's syndrome
A genetic disorder in males caused by having an extra X chromosome. Males with this disorder may have larger than normal breasts, a lack of facial and body hair, a rounded body type, and small testicles. They may learn to speak much later than other children and may have difficulty learning to read and write. Klinefelter's syndrome increases the risk of developing testicular cancer.

Korean acupuncture (...AK-yoo-PUNK-cher)
A type of acupuncture based on a form of Oriental medicine in which treatment is based on a person's constitution. According to this type of medicine, the constitution is the specific way a person's organs affect health and how he or she looks, thinks, behaves, and responds to treatment. Also called constitutional acupuncture.

KOS-862
A substance that is being studied in the treatment of cancer. It belongs to the families of drugs called mitotic inhibitors and epothilones. Also called epothilone D.

KPS
Karnofsky Performance Status. A standard way of measuring the ability of cancer patients to perform ordinary tasks. The Karnofsky Performance scores range from 0 to 100. A higher score means the patient is better able to carry out daily activities. KPS may be used to determine a patient's prognosis, to measure changes in a patient's ability to function, or to decide if a patient could be included in a clinical trial.

kretek
A cigarette made of a mixture of tobacco and clove.

KRN5500
An anticancer drug that belongs to a family of drugs called antitumor antibiotics. It is an anthracycline.

KRN7000
A drug being studied in the treatment of cancer. It is a biological response modifier that belongs to the family of drugs called glycosphingolipids or agelasphins.

Krukenberg tumor (KROO-ken-berg TOO-mer)
A tumor in the ovary caused by the spread of stomach cancer.

KSHV
Kaposi's sarcoma-associated herpesvirus. A type of herpesvirus that may cause Kaposi's sarcoma (a rare cancer that can cause skin lesions) and a type of lymphoma (cancer that begins in the lymph system), especially in patients who have a weak immune system. Also called human herpesvirus 8 (HHV8).

KW2189
A semisynthetic anticancer drug that belongs to the family of drugs called antitumor antibiotics.

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L-377,202
A substance that is being studied in the treatment of cancer.

L-778,123
An anticancer drug that belongs to the family of drugs called enzyme inhibitors. It may inhibit the transformation of normal cells into cancer cells.

L-carnitine
A form of carnitine, which is a substance made in the muscles and liver. It can be given as a supplement to prevent and treat carnitine deficiency in patients who are receiving chemotherapy for cancer or undergoing dialysis for kidney disease. Also called levocarnitine.

labial mucosa (LAY-bee-ul myoo-KOH-suh)
The inner lining of the lips.

laboratory study
Research done in a laboratory. These studies may use test tubes or animals to find out if a drug, procedure, or treatment is likely to be useful. Laboratory studies take place before any testing is done in humans.

laboratory test
A medical procedure that involves testing a sample of blood, urine, or other substance from the body. Tests can help determine a diagnosis, plan treatment, check to see if treatment is working, or monitor the disease over time.

lacrimal gland
A gland that secretes tears. The lacrimal glands are found in the upper, outer part of each eye socket.

lactate dehydrogenase (LAK-tayt dee-hy-DRAH-juh-nayz)
LDH. One of a group of enzymes found in the blood and other body tissues and involved in energy production in cells. An increased amount of LDH in the blood may be a sign of tissue damage and some types of cancer or other diseases. Also called lactic acid dehydrogenase.

lactic acid dehydrogenase
One of a group of enzymes found in the blood and other body tissues, and involved in energy production in cells. An increased amount in the blood may be a sign of tissue damage and some types of cancer or other diseases. Also called lactate dehydrogenase.

lactoferrin (LAK-toh-fayr-in)
A protein that is found in milk, tears, mucus, bile, and some white blood cells and is being studied in the treatment and prevention of cancer. It is involved in fighting against infection and inflammation and it acts as an antioxidant.

lactose
A type of sugar found in milk and milk products.

lactose intolerance
The inability to digest or absorb lactose, a type of sugar found in milk and other dairy products.

laetrile (LAY-eh-tril)
A substance found in the pits of many fruits such as apricots and papayas, and in other foods. It has been tried in some countries as a treatment for cancer, but it has not been shown to work in clinical studies. Laetrile is not approved for use in the United States. Also called amygdalin.

LAK cell
A white blood cell that is stimulated in a laboratory to kill tumor cells. Also called a lymphokine-activated killer cell.

lamina propria
A type of connective tissue found under the thin layer of tissues covering a mucous membrane.

lamivudine
A drug used to treat infection caused by viruses.

lamotrigine
A drug that is used to help control some types of seizures. It is being studied in the prevention of peripheral neuropathy caused by some chemotherapy drugs. It belongs to the family of drugs called anticonvulsants.

laparoscope (LA-puh-ruh-SKOPE)
A thin, tube-like instrument used to look at tissues and organs inside the abdomen. A laparoscope has a light and a lens for viewing and may have a tool to remove tissue.

laparoscopic prostatectomy (LA-puh-ruh-SKAH-pik prah-stuh-TEK-toh-mee)
Surgery to remove all or part of the prostate with the aid of a laparoscope. A laparoscope is a thin, tube-like instrument with a light and a lens for viewing. It may also have a tool to remove tissue to be checked under a microscope for signs of disease.

laparoscopic-assisted colectomy (LA-puh-ruh-SKAH-pik...koh-LEK-toh-mee)
Surgery done with the aid of a laparoscope to remove all or part of the colon through several small incisions made in the wall of the abdomen. A laparoscope is a thin, tube-like instrument with a light and a lens for viewing. It may also have a tool to remove tissue to be checked under a microscope for signs of disease. The laparoscope is inserted through one opening to guide the surgery. Surgical instruments are inserted through the other openings to perform the surgery. When only part of the colon is removed, it is called a partial colectomy.

laparoscopy (la-puh-ROSS-koh-pee)
A procedure that uses a laparoscope, inserted through the abdominal wall, to examine the inside of the abdomen. A laparoscope is a thin, tube-like instrument with a light and a lens for viewing. It may also have a tool to remove tissue to be checked under a microscope for signs of disease.

laparotomy (lap-a-RAH-toe-mee)
A surgical incision made in the wall of the abdomen.

lapatinib
A substance that is being studied in the treatment of cancer. It belongs to the family of drugs called ErbB-2 and EGFR dual tyrosine kinase inhibitors. Also called GW572016 and Tykerb.

lappa
Arctium lappa. A plant whose seeds and root have been used in some cultures to treat certain medical problems. It may have antioxidant effects. Also called burdock and happy major.

large cell carcinoma (...KAR-sih-NOH-muh)
Lung cancer in which the cells are large and look abnormal when viewed under a microscope.

large granular lymphocyte
A type of white blood cell that contains granules with enzymes that can kill tumor cells or microbial cells. Also called a natural killer cell.

large intestine
The long, tube-like organ that is connected to the small intestine at one end and the anus at the other. The large intestine has four parts: cecum, colon, rectum, and anal canal. Partly digested food moves through the cecum into the colon, where water and some nutrients and electrolytes are removed. The remaining material, solid waste called stool, moves through the colon, is stored in the rectum, and leaves the body through the anal canal and anus.

laryngeal (luh-RIN-jee-ul)
Having to do with the larynx.

laryngeal cancer (luh-RIN-jee-ul KAN-ser)
Cancer that forms in tissues of the larynx (area of the throat that contains the vocal cords and is used for breathing, swallowing, and talking). Most laryngeal cancers are squamous cell carcinomas (cancer that begins in flat cells lining the larynx).

laryngectomee (lair-in-JEK-toe-mee)
A person whose larynx (voice box) has been removed.

laryngectomy (LAIR-in-JEK-tuh-mee)
An operation to remove all or part of the larynx (voice box).

laryngitis
Inflammation of the larynx.

laryngoscope (luh-RING-goh-SKOPE)
A thin, tube-like instrument used to examine the larynx (voice box). A laryngoscope has a light and a lens for viewing and may have a tool to remove tissue.

laryngoscopy (LAIR-in-GOSS-kuh-pee)
Examination of the larynx (voice box) with a mirror (indirect laryngoscopy) or with a laryngoscope (direct laryngoscopy).

larynx (LAIR-inks)
The area of the throat containing the vocal cords and used for breathing, swallowing, and talking. Also called the voice box.

laser (LAY-zer)
A device that concentrates light into an intense, narrow beam used to cut or destroy tissue. It is used in microsurgery, photodynamic therapy, and for a variety of diagnostic purposes.

laser acupuncture (LAY-zer AK-yoo-PUNK-cher)
The use of a low-level laser beam instead of an acupuncture needle to stimulate an acupuncture point.

laser surgery
A surgical procedure that uses the cutting power of a laser beam to make bloodless cuts in tissue or to remove a surface lesion such as a tumor.

laser therapy
The use of an intensely powerful beam of light to kill cancer cells.

lassitude (LA-sih-tood)
A feeling of tiredness, weakness, and lack of interest in daily activities.

late effects
Side effects of cancer treatment that appear months or years after treatment has ended. Late effects include physical and mental problems and second cancers.

latent
Describes a condition that is present but not active or causing symptoms.

lavender (LA-vun-der)
A plant with aromatic leaves and flowers that is a member of the mint family. Oil from the flowers has been used in some cultures to treat certain medical problems, to keep insects away, and to wash in. It is also used in aromatherapy. Perillyl alcohol, a substance found in lavender, is being studied in cancer prevention and treatment. Also called English lavender and true lavender. The scientific name is Lavandula angustifolia.

laxative
A substance that promotes bowel movements.

LCIS
Lobular carcinoma in situ. Abnormal cells found in the lobules of the breast. This condition seldom becomes invasive cancer; however, having lobular carcinoma in situ increases one's risk of developing breast cancer in either breast.

LDH
Lactate dehydrogenase. One of a group of enzymes found in the blood and other body tissues, and involved in energy production in cells. An increased amount in the blood may be a sign of tissue damage and some types of cancer or other diseases. Also called lactic acid dehydrogenase.

lectin
A complex molecule that has both protein and sugars. Lectins are able to bind to the outside of a cell and cause biochemical changes in it. Lectins are made by both animals and plants.

LED therapy
Light-emitting diode therapy. Treatment with drugs that become active and may kill cancer cells when exposed to light. LED therapy is a type of photodynamic therapy, which uses a special type of light to activate the drug.

LEEP
Loop electrosurgical excision procedure. A technique that uses electric current passed through a thin wire loop to remove abnormal tissue. Also called loop excision.

leflunomide
An anticancer drug that works by inhibiting a cancer cell growth factor. Also called SU101.

legal aid organization
A group or agency that gives legal help to people with low incomes. Health legal aid workers help people with issues related to getting good healthcare, and getting insurance to cover certain patients and conditions.

leiomyoma
A benign smooth muscle tumor, usually in the uterus or gastrointestinal tract. Also called fibroid.

leiomyosarcoma
A malignant (cancerous) tumor of smooth muscle cells that can arise almost anywhere in the body, but is most common in the uterus, abdomen, or pelvis.

lenalidomide
A substance that is being studied in the treatment of cancer. It is similar to thalidomide. It belongs to the family of drugs called angiogenesis inhibitors. Also called CC-5013.

lentinan
A beta-glucan (a type of polysaccharide) from the mushroom Lentinus edodes (shiitake mushroom). It has been studied in Japan as a treatment for cancer.

LEP-ETU
A form of the anticancer drug paclitaxel that may have fewer side effects and work better than paclitaxel. It is being studied in the treatment of cancer. It belongs to the family of drugs called mitotic inhibitors. Also called PNU-93914 and paclitaxel liposome.

lepirudin
A drug that inhibits blood clotting. It is being studied in cancer treatment.

leptomeningeal
Having to do with the two innermost layers of tissues that cover the brain and spinal cord.

leptomeningeal cancer
A tumor that involves the tissues that cover the brain and spinal cord.

leptomeningeal metastases
Cancer that has spread from the original (primary) tumor to the tissues that cover the brain and spinal cord.

leridistim
A substance that is being studied for its ability to stimulate the production of blood cells during chemotherapy. It belongs to the family of drugs called colony-stimulating factors. Also known as SC-70935.

lerisetron
A drug that prevents or reduces nausea and vomiting.

lesion (LEE-zhun)
An area of abnormal tissue. A lesion may be benign (noncancerous) or malignant (cancerous).

letrozole
An anticancer drug that belongs to the family of drugs called nonsteroidal aromatase inhibitors. Letrozole is used to decrease estrogen production and suppress the growth of estrogen-dependent tumors.

leucovorin
A drug used to protect normal cells from high doses of the anticancer drug methotrexate. It is also used to increase the antitumor effects of fluorouracil and tegafur-uracil, an oral treatment alternative to intravenous fluorouracil.

leukapheresis
Removal of the blood to collect specific blood cells; the remaining blood is returned to the body.

leukemia (loo-KEE-mee-a)
Cancer that starts in blood-forming tissue such as the bone marrow, and causes large numbers of blood cells to be produced and enter the bloodstream.

leukocyte (LOO-ko-site)
A white blood cell. Refers to a blood cell that does not contain hemoglobin. White blood cells include lymphocytes, neutrophils, eosinophils, macrophages, and mast cells. These cells are made by bone marrow and help the body fight infection and other diseases.

leukopenia (LOO-ko-PEE-nya)
A condition in which the number of leukocytes (white blood cells) in the blood is reduced.

leukoplakia (loo-ko-PLAY-kee-a)
An abnormal patch of white tissue that forms on mucous membranes in the mouth and other areas of the body. It may become cancerous. Tobacco (smoking and chewing) and alcohol may increase the risk of leukoplakia in the mouth.

leuprolide (LOO-pro-lide)
A drug that belongs to the family of drugs called gonadotropin-releasing hormone analogs. It is used to block hormone production in the ovaries or testicles.

leuvectin
An agent that delivers the gene for interleukin-2 (IL-2) into cells to increase production of IL-2 by the cells.

levamisole
An antiparasitic drug that is also being studied in cancer therapy with fluorouracil.

levels of evidence (LEH-vulz uv EH-vih-dents)
A ranking system used to describe the strength of the results measured in a clinical trial or research study. The design of the study (such as a case report for an individual patient or a randomized double-blinded controlled clinical trial) and the endpoints measured (such as survival or quality of life) affect the strength of the evidence.

levocarnitine
A form of carnitine, which is a substance made in the muscles and liver. It can be given as a supplement to prevent and treat carnitine deficiency in patients who are receiving chemotherapy for cancer or undergoing dialysis for kidney disease. Also called L-carnitine.

levofloxacin
A substance used to treat bacterial infections. It belongs to the family of drugs called quinolone antibiotics.

Lexapro
A drug used to treat depression and certain anxiety disorders. It belongs to the family of drugs called selective serotonin reuptake inhibitors (SSRIs). Also called escitalopram.

LGD1069
An anticancer drug used to decrease the growth of some types of cancer cells. It belongs to the family of drugs called retinoids. Also called bexarotene.

LH-RH
Luteinizing hormone-releasing hormone. A hormone that stimulates the production of sex hormones in men and women.

Lhermitte's sign (lair-MEETS)
A sensation similar to an electrical shock radiating from the back of the head down the spine as the neck is bent forward.

Li-Fraumeni syndrome
A rare, inherited predisposition to multiple cancers, caused by an alteration in the p53 tumor suppressor gene.

liarozole
An anticancer drug that promotes differentiation by increasing the levels of retinoic acid within the tumor.

libido (lih-BEE-doh)
Sexual desire.

lidocaine (LYE-doe-kane)
A substance that is used to relieve pain by blocking signals at the nerve endings in skin. It can also be given intravenously to stop heart arrhythmias. It belongs to the families of drugs called local anesthetics and antiarrhythmics.

ligation (lye-GAY-shun)
The process of tying off blood vessels so that blood cannot flow to a part of the body or to a tumor.

light microscope
A microscope (device to magnify small objects) in which objects are lit directly by white light.

light-emitting diode therapy
LED therapy. Treatment with drugs that become active and may kill cancer cells when exposed to light. LED therapy is type of photodynamic therapy which uses a special type of light to activate the drug.

lignan
A member of a group of substances found in plants that have shown estrogenic and anticancer effects. Lignans have been used in some cultures to treat certain medical problems.

limb perfusion (per-FYOO-zhun)
A technique that may be used to deliver anticancer drugs directly to an arm or leg. The flow of blood to and from the limb is temporarily stopped with a tourniquet, and anticancer drugs are put directly into the blood of the limb. This allows the person to receive a high dose of drugs in the area where the cancer occurred. Also called isolated limb perfusion.

limbic system (LIM-bik SIS-tem)
A network of structures in the brain involved in memory and emotions.

limited-stage small cell lung cancer
Cancer is found in one lung, the tissues between the lungs, and nearby lymph nodes only.

linac
A machine that uses electricity to form a stream of fast-moving subatomic particles. This creates high-energy radiation that may be used to treat cancer. Also called linear accelerator and MeV linear accelerator (mega-voltage linear accelerator).

linear accelerator
A machine that uses electricity to form a stream of fast-moving subatomic particles. This creates high-energy radiation that may be used to treat cancer. Also called linac and MeV linear accelerator (mega-voltage linear accelerator).

linseed
The seed of the flax plant. It is a rich source of omega-3 fatty acid, fiber, and a compound called lignin. It is being studied in the prevention of prostate cancer. Also called flaxseed.

liothyronine sodium
A thyroid hormone. Also called triiodothyronine or T-3.

lipid
Fat.

lipoma (lih-POH-muh)
A benign (not cancer) tumor made of fat cells.

lipophilic
Able to dissolve, be dissolved in, or absorb lipids (fats).

liposarcoma
A rare cancer of the fat cells.

liposomal
A drug preparation that contains the active drug in very tiny fat particles. This fat-encapsulated drug is absorbed better, and its distribution to the tumor site is improved.

liposomal SN-38 (LIH-poh-SOH-mul...)
A form of the anticancer drug irinotecan that may have fewer side effects and work better than irinotecan alone. It is being studied in the treatment of cancer. It belongs to the family of drugs called irinotecan (CPT-11) derivatives.

liquid-based Pap test
A type of Pap test. A Pap test is a procedure in which cells are scraped from the cervix for examination under a microscope. It is used to detect cancer or changes that may lead to cancer. A Pap test can also show noncancerous conditions, such as infection or inflammation. In a liquid-based Pap test, the cells are rinsed into a small container of liquid. The cells are then placed onto slides by a special machine and examined under a microscope to see if the cells are abnormal.

lisofylline
A drug that may protect healthy cells from chemotherapy and radiation without inhibiting the effects of these therapies on tumor cells.

liver
A large organ located in the upper abdomen. The liver cleanses the blood and aids in digestion by secreting bile.

liver cancer
A disease in which malignant (cancer) cells are found in the tissues of the liver.

liver function test
A blood test to measure the blood levels of certain substances released by the liver. A high or low level of certain substances can be a sign of liver disease.

liver metastases
Cancer that has spread from the original (primary) tumor to the liver.

liver scan
An image of the liver created on a computer screen or on film. A radioactive substance is injected into a blood vessel and travels through the bloodstream. It collects in the liver, especially in abnormal areas, and can be detected by the scanner.

living will
A type of legal advance directive in which a person describes specific treatment guidelines that are to be followed by health care providers if he or she becomes terminally ill and cannot communicate. A living will usually has instructions about whether to use aggressive medical treatment to keep a person alive (such as CPR, artificial nutrition, use of a respirator).

LMB-1 immunotoxin
A toxic substance linked to an antibody that attaches to tumor cells and kills them.

LMB-2 immunotoxin
A toxic substance linked to an antibody that attaches to tumor cells and kills them.

LMB-7 immunotoxin
A toxic substance linked to an antibody that attaches to tumor cells and kills them.

LMB-9 immunotoxin
A toxic substance linked to an antibody that attaches to tumor cells and kills them.

lobaplatin
An anticancer drug that belongs to the family of drugs called platinum compounds.

lobe
A portion of an organ, such as the liver, lung, breast, thyroid, or brain.

lobectomy ( loh-BEK-tuh-mee)
Surgery to remove a whole lobe (section) of an organ (such as a lung, liver, brain, or thyroid gland).

lobradimil
A substance that is being studied for its ability to help other drugs reach the brain. It belongs to the family of drugs called bradykinin agonists. Also called RMP-7.

lobular carcinoma
Cancer that begins in the lobules (the glands that make milk) of the breast. Lobular carcinoma in situ (LCIS) is a condition in which abnormal cells are found only in the lobules. When cancer has spread from the lobules to surrounding tissues, it is invasive lobular carcinoma. LCIS does not become invasive lobular carcinoma very often, but having LCIS in one breast increases the risk of developing invasive cancer in either breast.

lobular carcinoma in situ (LOB-yoo-lar KAR-sih-NOH-muh in SYE-too)
LCIS. A condition in which abnormal cells are found in the lobules of the breast. LCIS seldom becomes invasive cancer; however, having lobular carcinoma in situ in one breast increases the risk of developing breast cancer in either breast.

lobule (LOB-yule)
A small lobe or a subdivision of a lobe.

local anesthesia (an-es-THEE-zha)
Drugs that cause a temporary loss of feeling in one part of the body. The patient remains awake but has no feeling in the part of the body treated with the anesthetic.

local cancer
An invasive malignant cancer confined entirely to the organ where the cancer began.

local therapy
Treatment that affects cells in the tumor and the area close to it.

localization (LO-kal-ih-ZAY-shun)
The process of determining or marking the location or site of a lesion or disease. May also refer to the process of keeping a lesion or disease in a specific location or site.

localized
Restricted to the site of origin, without evidence of spread.

localized gallbladder cancer
Cancer found only in the tissues that make up the wall of the gallbladder. Localized gallbladder cancer can be removed completely in an operation.

localized malignant mesothelioma
Cancer is found in the lining of the chest wall and may also be found in the lining of the lung, the lining of the diaphragm (the thin muscle below the lungs and heart that separates the chest from the abdomen), or the lining of the sac that covers the heart on the same side of the chest. Also called stage I malignant mesothelioma.

locally advanced cancer
Cancer that has spread only to nearby tissues or lymph nodes.

locus (LOH-kuss)
Specific place where something is located or occurs. It may refer to a specific place on the body (such as an acupuncture point) or the place on a chromosome where a specific gene is found.

lometrexol
A substance that is being studied as a treatment for cancer. It belongs to the family of drugs called antifolates.

lomustine
An anticancer drug that belongs to the family of drugs called alkylating agents.

lonafarnib
An anticancer drug that belongs to the family of drugs called enzyme inhibitors. Also called SCH 66336.

loop electrosurgical excision procedure (loop ee-LEK-troh-SER-jih-kul ek-SIH-zhun proh-SEE-jer)
LEEP. A technique that uses electric current passed through a thin wire loop to remove abnormal tissue. Also called loop excision.

loop excision (ek-SI-zhun)
A technique that uses electric current passed through a thin wire loop to remove abnormal tissue. Also called loop electrosurgical excision procedure (LEEP).

loperamide hydrochloride
An antidiarrheal drug.

lorazepam (lor-AZ-uh-pam)
A drug that is used to treat anxiety and certain seizure disorders (such as epilepsy), and to prevent nausea and vomiting caused by chemotherapy. It belongs to the families of drugs called antiemetics and benzodiazepines.

losoxantrone
An anticancer drug that belongs to the family of drugs called antipyrazoles.

low grade
When referring to cancerous and precancerous growths, a term used to describe cells that look nearly normal under a microscope. These cells are less likely to grow and spread quickly than cells in high-grade cancerous or precancerous growths.

low-grade lymphoma
A type of lymphoma that tends to grow and spread slowly, and has few symptoms. Also called indolent lymphoma.

low-grade squamous intraepithelial lesion
LSIL. A condition in which the cells of the uterine cervix are slightly abnormal. LSIL is not cancer.

lower GI series
X-rays of the colon and rectum (lower gastrointestinal tract) that are taken after a person is given a barium enema.

LSIL
Low-grade squamous intraepithelial lesion. A condition in which the cells of the uterine cervix are slightly abnormal. LSIL is not cancer.

LU 79553
An anticancer drug that kills cancer cells by affecting DNA synthesis.

LU-103793
An anticancer drug that reduces the risk of tumor cell growth and reproduction.

lubricant (LOO-brih-kant)
An oily or slippery substance.

lumbar puncture
A procedure in which a needle is put into the lower part of the spinal column to collect cerebrospinal fluid or to give anticancer drugs intrathecally. Also called a spinal tap.

lumen
The cavity or channel within a tube or tubular organ such as a blood vessel or the intestine.

lumpectomy (lump-EK-toe-mee)
Surgery to remove the tumor and a small amount of normal tissue around it.

lung
One of a pair of organs in the chest that supplies the body with oxygen, and removes carbon dioxide from the body.

lung cancer (lung KAN-ser)
Cancer that forms in tissues of the lung, usually in the cells lining air passages. The two main types are small cell lung cancer and non-small cell lung cancer. These types are diagnosed based on how the cells look under a microscope.

lung metastases
Cancer that has spread from the original (primary) tumor to the lung.

lupus
A chronic, inflammatory, connective tissue disease that can affect the joints and many organs, including the skin, heart, lungs, kidneys, and nervous system. It can cause many different symptoms; however, not everyone with lupus has all of the symptoms. Also called systemic lupus erythematosus (SLE).

lurtotecan
An anticancer drug that belongs to the family of drugs called topoisomerase inhibitors.

luteinizing hormone-releasing hormone
LH-RH. A hormone that stimulates the production of sex hormones in men and women.

luteinizing hormone-releasing hormone agonist (LOO-tin-eye-zing. . .AG-o-nist)
LH-RH agonist. A drug that inhibits the secretion of sex hormones. In men, LH-RH agonist causes testosterone levels to fall. In women, LH-RH agonist causes the levels of estrogen and other sex hormones to fall.

lutetium texaphyrin
A substance that is being studied in the treatment of cancer using photodynamic therapy. It belongs to the family of drugs called metallotexaphyrins. Also called motexafin lutetium.

Luvox
A drug used to treat obsessive-compulsive disorder. It belongs to the families of drugs called antidepressant agents and selective serotonin reuptake inhibitors (SSRIs). Also called fluvoxamine.

LY231514
A drug that is used to treat malignant pleural mesothelioma and advanced non-small cell lung cancer and is being studied in the treatment of other types of cancer. It belongs to the family of drugs called enzyme inhibitors. Also called Alimta and pemetrexed disodium.

LY293111
A substance that is being studied as a treatment for cancer. It belongs to the family of drugs called leukotriene B4 receptor antagonists.

LY317615
A substance that is being studied in the treatment of cancer. It belongs to the families of drugs called protein kinase C inhibitors and angiogenesis inhibitors. Also called enzastaurin.

LY335979
A substance that is being studied for its ability to reverse resistance to chemotherapy. Also called zosuquidar trihydrochloride.

LY353381 hydrochloride
A hormone substance used in the treatment of some types of cancer.

lycopene (LIE-kuh-peen)
A red pigment found in tomatoes and some fruits. It is an antioxidant and may help prevent some types of cancer.

lymph (limf)
The clear fluid that travels through the lymphatic system and carries cells that help fight infections and other diseases. Also called lymphatic fluid.

lymph gland
A rounded mass of lymphatic tissue that is surrounded by a capsule of connective tissue. Lymph glands filter lymph (lymphatic fluid), and they store lymphocytes (white blood cells). They are located along lymphatic vessels. Also called a lymph node.

lymph node (limf node)
A rounded mass of lymphatic tissue that is surrounded by a capsule of connective tissue. Lymph nodes filter lymph (lymphatic fluid), and they store lymphocytes (white blood cells). They are located along lymphatic vessels. Also called a lymph gland.

lymph node dissection (limf node dis-EK-shun)
A surgical procedure in which the lymph nodes are removed and examined to see whether they contain cancer. For a regional lymph node dissection, some of the lymph nodes in the tumor area are removed; for a radical lymph node dissection, most or all of the lymph nodes in the tumor area are removed. Also called lymphadenectomy.

lymph node drainage
The flow of lymph from an area of tissue into a particular lymph node.

lymph node mapping
The use of dyes and radioactive substances to identify lymph nodes that may contain tumor cells. Also called lymphatic mapping.

lymph vessel (limf)
A thin tube that carries lymph (lymphatic fluid) and white blood cells through the lymphatic system. Also called lymphatic vessel.

lymphadenectomy
A surgical procedure in which the lymph nodes are removed and examined to see whether they contain cancer. For a regional lymphadenectomy, some of the lymph nodes in the tumor area are removed; for a radical lymphadenectomy, most or all of the lymph nodes in the tumor area are removed. Also called lymph node dissection.

lymphadenopathy
Disease or swelling of the lymph nodes.

lymphangiogram (lim-FAN-jee-o-gram)
An x-ray of the lymphatic system. A dye is injected into a lymphatic vessel and travels throughout the lymphatic system. The dye outlines the lymphatic vessels and organs on the x-ray.

lymphangiography (lim-FAN-jee-AH-gra-fee)
An x-ray study of the lymphatic system. A dye is injected into a lymphatic vessel and travels throughout the lymphatic system. The dye outlines the lymphatic vessels and organs on the x-ray.

lymphangiosarcoma
A type of cancer that begins in the cells that line lymph vessels.

lymphatic basin
A group of lymph nodes that receives and filters lymph that flows from a certain area of the body. Special dyes may be used to stain and identify the lymphatic basin in the tissues around a tumor, so that lymph nodes that may contain cancer can be removed and checked by a pathologist.

lymphatic fluid (lim-FAT-ik)
The clear fluid that travels through the lymphatic system and carries cells that help fight infections and other diseases. Also called lymph.

lymphatic mapping
The use of dyes and radioactive substances to identify lymph nodes that may contain tumor cells. Also called lymph node mapping.

lymphatic system (lim-FAT-ik SIS-tem)
The tissues and organs that produce, store, and carry white blood cells that fight infections and other diseases. This system includes the bone marrow, spleen, thymus, lymph nodes, and lymphatic vessels (a network of thin tubes that carry lymph and white blood cells). Lymphatic vessels branch, like blood vessels, into all the tissues of the body.

lymphatic vessel (lim-FAT-ik)
A thin tube that carries lymph (lymphatic fluid) and white blood cells through the lymphatic system. Also called lymph vessel.

lymphedema (LIMF-eh-DEE-ma)
A condition in which excess fluid collects in tissue and causes swelling. It may occur in the arm or leg after lymph vessels or lymph nodes in the underarm or groin are removed or treated with radiation.

lymphoblast
A lymphocyte that has gotten larger after being stimulated by an antigen. Lymphoblasts look like immature lymphocytes, and were once thought to be precursor cells.

lymphocyte (LIM-fo-site)
A type of white blood cell. Lymphocytes have a number of roles in the immune system, including the production of antibodies and other substances that fight infection and diseases.

lymphocytic (lim-fo-SIT-ik)
Referring to lymphocytes, a type of white blood cell.

lymphocytic leukemia
A type of cancer in which the bone marrow makes too many lymphocytes (white blood cells).

lymphoepithelioma (LIM-fo-EP-ih-THEE-lee-O-ma)
A type of cancer that begins in the tissues covering the nasopharynx (the upper part of the throat behind the nose).

lymphography
An x-ray study of lymph nodes and lymphatic vessels made visible by the injection of a special dye.

lymphoid (LIM-foyd)
Referring to lymphocytes, a type of white blood cell. Also refers to tissue in which lymphocytes develop.

lymphokine-activated killer cell
A white blood cell that is stimulated in a laboratory to kill tumor cells. Also called an LAK cell.

lymphoma (lim-FO-ma)
Cancer that begins in cells of the immune system. There are two basic categories of lymphomas. One kind is Hodgkin's lymphoma, which is marked by the presence of a type of cell called the Reed-Sternberg cell. The other category is non-Hodgkin's lymphomas, which includes a large, diverse group of cancers of immune system cells. Non-Hodgkin's lymphomas can be further divided into cancers that have an indolent (slow-growing) course and those that have an aggressive (fast-growing) course. These subtypes behave and respond to treatment differently. Both Hodgkin's and non-Hodgkin's lymphomas can occur in children and adults, and prognosis and treatment depend on the stage and the type of cancer.

lymphomatoid granulomatosis
Destructive growth of lymph cells, usually involving the lungs, skin, kidneys, and central nervous system. Grades I and II are not considered cancerous, but grade III is considered a lymphoma.

lymphoplasmacytic lymphoma (LIM-foh-plaz-muh-SIH-tik lim-FOH-muh)
An indolent (slow-growing) type of non-Hodgkin's lymphoma marked by abnormal levels of IgM antibodies in the blood and an enlarged liver, spleen, or lymph nodes. Also called Waldenstrom's macroglobulinemia.

lymphoproliferative disorder
A disease in which cells of the lymphatic system grow excessively. Lymphoproliferative disorders are often treated like cancer.

lymphosarcoma
An obsolete term for a malignant tumor of lymphatic tissue.

lymphoscintigraphy (lim-fo-sin-TIG-ruh-fee)
A method used to identify the sentinel lymph node (the first draining lymph node near a tumor). A radioactive substance that can be taken up by lymph nodes is injected at the site of the tumor, and a doctor follows the movement of this substance on a computer screen. Once the lymph nodes that have taken up the substance are identified, they can be removed and examined to see if they contain tumor cells.

Lynch syndrome
An inherited disorder in which affected individuals have a higher-than-normal chance of developing colon cancer and certain other types of cancer, usually before the age of 60. Also called hereditary nonpolyposis colon cancer.

lysis
In biology, lysis refers to the breakdown of a cell caused by damage to its plasma (outer) membrane. Lysis can be caused by chemical or physical means (for example, strong detergents or high-energy sound waves) or by an infection.

lysosome
A sac-like compartment inside a cell that has enzymes that can break down cellular components that need to be destroyed.

lytic
Having to do with lysis. In biology, lysis refers to the disintegration of a cell by disruption of its plasma membrane. Lysis can be caused by chemical or physical means (e.g., high-energy sound waves) or by a virus infection.

lytic lesion
Destruction of an area of bone due to a disease process, such as cancer.

ABCDEFGHIJKLMNOPQRSTUVWXYZ

M protein
An antibody or part of an antibody found in unusually large amounts in the blood or urine of people with multiple myeloma and other types of plasma cell tumors. Also called monoclonal protein.

M200
A monoclonal antibody that is being studied in the treatment of some types of cancer. Monoclonal antibodies are made in the laboratory and can locate and bind to cancer cells. M200 binds to a protein that is found on cells that line some tumor blood vessels. It belongs to the family of drugs called angiogenesis inhibitors. Also called volociximab.

ma huang (mah-hwahng)
Ephedra sinica. A shrub native to China and India. The stems and roots are used in traditional medicine as a diuretic and for asthma, bronchitis, and cough. It has also been promoted as a decongestant, a weight loss aid, and as a supplement to increase energy. Ma huang may cause high blood pressure, increased heart rate, or death if used with certain drugs, and may reduce the effects of certain drugs used to treat cancer and other diseases. The U.S. Food and Drug Administration has banned the sale of dietary supplements that contain ma huang. Also called ephedra.

macroglobulinemia (MAK-ro-GLOB-u-li-NE-me-uh)
A condition in which the blood contains high levels of large proteins and is too thick to flow through small blood vessels. One type is Waldenstrom's macroglobulinemia, which is a type of cancer.

macrophage
A type of white blood cell that surrounds and kills microorganisms, removes dead cells, and stimulates the action of other immune system cells.

mafosfamide
A form of cyclophosphamide that can be administered as an intrathecal infusion. Mafosfamide is being studied as an anticancer drug. It belongs to the family of drugs called alkylating agents.

MAGE-3
A gene found in some types of tumors.

magnesium
In medicine, a mineral used by the body to help maintain muscles, nerves, and bones. It is also used in energy metabolism and protein synthesis.

magnetic resonance imaging (mag-NET-ik REZ-o-nans IM-a-jing)
MRI. A procedure in which radio waves and a powerful magnet linked to a computer are used to create detailed pictures of areas inside the body. These pictures can show the difference between normal and diseased tissue. MRI makes better images of organs and soft tissue than other scanning techniques, such as CT or x-ray. MRI is especially useful for imaging the brain, spine, the soft tissue of joints, and the inside of bones. Also called nuclear magnetic resonance imaging.

magnetic resonance perfusion imaging
A special type of magnetic resonance imaging (MRI) that uses an injected dye in order to see blood flow through tissues. Also called perfusion magnetic resonance imaging.

magnetic resonance spectroscopic imaging
MRSI. A noninvasive imaging method that provides information about cellular activity (metabolic information). It is used along with magnetic resonance imaging (MRI) which provides information about the shape and size of the tumor (spacial information). Also called 1H-nuclear magnetic resonance spectroscopic imaging and proton magnetic resonance spectroscopic imaging.

magnetic-targeted carrier
A tiny bead made from particles of iron and carbon that can be attached to an anticancer drug. A magnet applied from outside the body then can direct the drug to the tumor site. This can keep a larger dose of the drug at the tumor site for a longer period of time, and help protect healthy tissue from the side effects of chemotherapy.

maidenhair tree (MAY-din-HAYR...)
A tree native to China. Substances taken from the leaves and seeds have been used in some cultures to treat certain medical problems. Maidenhair tree has been studied in the prevention and treatment of Alzheimer's disease, dementia, certain blood vessel diseases, and memory loss. It may cause bleeding or high blood pressure when used with certain drugs. Also called ginkgo biloba and ginkgo.

mainstream medicine
A system in which medical doctors and other healthcare professionals (such as nurses, pharmacists, and therapists) treat symptoms and diseases using drugs, radiation, or surgery. Also called conventional medicine, Western medicine, orthodox medicine, biomedicine, and allopathic medicine.

maintenance therapy
Treatment that is given to help a primary (original) treatment keep working. Maintenance therapy is often given to help keep cancer in remission.

malabsorption syndrome
A group of symptoms such as gas, bloating, abdominal pain, and diarrhea resulting from the body's inability to properly absorb nutrients.

male breast cancer (male brest KAN-ser)
Cancer that forms in tissues of the breast in men. Most male breast cancer begins in cells lining the ducts. It is very rare and usually affects older men.

malignancy
A cancerous tumor that can invade and destroy nearby tissue and spread to other parts of the body.

malignant (ma-LIG-nant)
Cancerous. Malignant tumors can invade and destroy nearby tissue and spread to other parts of the body.

malignant ascites
A condition in which fluid containing cancer cells collects in the abdomen.

malignant fibrous cytoma
A soft tissue sarcoma that usually occurs in the limbs, most commonly the legs, and may also occur in the abdomen. Also called malignant fibrous histiocytoma.

malignant fibrous histiocytoma
A soft tissue sarcoma that usually occurs in the limbs, most commonly the legs, and may also occur in the abdomen. Also called malignant fibrous cytoma.

malignant meningioma
A rare, quickly growing tumor that occurs in the membranes that cover and protect the brain and spinal cord (meninges).

malignant mesothelioma
A rare type of cancer in which malignant cells are found in the sac lining the chest or abdomen. Exposure to airborne asbestos particles increases one's risk of developing malignant mesothelioma.

malignant mixed Mullerian tumor
MMMT. A rare type of tumor that is a mixture of carcinoma and sarcoma cells. MMMT usually occurs in the uterus.

malignant peripheral nerve sheath tumor
MPNST. A type of soft tissue sarcoma that develops in cells that form a protective sheath (covering) around peripheral nerves, which are nerves that are outside of the central nervous system (brain and spinal cord).

malnutrition
A disorder caused by a lack of proper nutrition or an inability to absorb nutrients from food.

malondialdehyde
A byproduct of lipid (fat) metabolism in the body. It is also found in many foods and can be present in high amounts in rancid food.

MALT lymphoma
Mucosa-associated lymphoid tissue lymphoma. A type of cancer that arises in cells in mucosal tissue that are involved in antibody production.

mammary
Having to do with the breast.

mammary dysplasia (MA-muh-ree dis-PLAY-zhuh)
A common condition marked by benign (noncancerous) changes in breast tissue. These changes may include irregular lumps or cysts, breast discomfort, sensitive nipples, and itching. These symptoms may change throughout the menstrual cycle and usually stop after menopause. Also called benign breast disease, fibrocystic breast disease, and fibrocystic breast changes.

mammary gland
Glandular organ located on the chest. The mammary gland is made up of connective tissue, fat, and breast tissue that contains the glands that can make milk. Also called breast.

mammogram (MAM-o-gram)
An x-ray of the breast.

mammography (mam-OG-ra-fee)
The use of x-rays to create a picture of the breast.

Mammotome
A device that uses a computer-guided probe to perform breast biopsies. A Mammotome biopsy can be done on an outpatient basis with a local anesthetic, removes only a small amount of healthy tissue, and doesn't require sutures (stitches) because the incision is very small.

mantle cell lymphoma (MAN-tul sel lim-FOH-muh)
An aggressive (fast-growing) type of B-cell non-Hodgkin's lymphoma that usually occurs in middle-aged or older adults. It is marked by small- to medium-size cancer cells that may be in the lymph nodes, spleen, bone marrow, blood, and gastrointestinal system.

mantle field (MAN-tul)
The area of the neck, chest, and lymph nodes in the armpit that are exposed to radiation.

margin
The edge or border of the tissue removed in cancer surgery. The margin is described as negative or clean when the pathologist finds no cancer cells at the edge of the tissue, suggesting that all of the cancer has been removed. The margin is described as positive or involved when the pathologist finds cancer cells at the edge of the tissue, suggesting that all of the cancer has not been removed.

marijuana
A type of plant. Extracts of marijuana are being studied for their ability to control severe nausea and vomiting caused by chemotherapy and/or opioid drugs such as morphine.

marimastat
An anticancer drug that belongs to the family of drugs called angiogenesis inhibitors. Marimastat is a matrix metalloproteinase inhibitor.

marker
A diagnostic indication that disease may develop.

massage therapy (muh-SAZH THAYR-uh-pee)
A treatment in which the soft tissues of the body are kneaded, rubbed, tapped, and stroked. Massage therapy may help people relax, relieve stress and pain, lower blood pressure, and improve circulation. It is being studied in the treatment of cancer symptoms such as lack of energy, pain, swelling, and depression.

mast cell
A type of white blood cell.

mast cell tumor
A growth or lump of mast cells (a type of white blood cell). Mast cell tumors can involve the skin, subcutaneous tissue, and muscle tissue. Also called mastocytoma.

mastectomy (mas-TEK-toe-mee)
Surgery to remove the breast (or as much of the breast tissue as possible).

mastocytoma
A growth or lump of mast cells (a type of white blood cell). Mast cell tumors can involve the skin, subcutaneous tissue, and muscle tissue. Also called mast cell tumor.

maternal (muh-TUR-nul)
Having to do with or coming from the mother.

matrix metalloproteinase
A member of a group of enzymes that can break down proteins, such as collagen, that are normally found in the spaces between cells in tissues (i.e., extracellular matrix proteins). Because these enzymes need zinc or calcium atoms to work properly, they are called metalloproteinases. Matrix metalloproteinases are involved in wound healing, angiogenesis, and tumor cell metastasis.

mature T-cell lymphoma
One of a group of aggressive (fast-growing) non-Hodgkin's lymphomas that begin in mature T lymphocytes (T cells that have matured in the thymus gland and gone to other lymphatic sites in the body, including lymph nodes, bone marrow, and spleen.) Also called peripheral T-cell lymphoma.

mature teratoma (muh-CHOOR TAYR-uh-TOH-muh)
A type of benign (noncancerous) germ cell tumor (type of tumor that begins in the cells that give rise to sperm or eggs) that often contains several different types of tissue such as hair, muscle, and bone. Also called a dermoid cyst.

matuzumab
A monoclonal antibody that is being studied in the treatment of some types of cancer. Monoclonal antibodies are made in the laboratory and can locate and bind to cancer cells. Matuzumab binds to the epithelial growth factor receptor (EGFR) on tumor cells and blocks growth signals. Also called EMD 72000.

MDL 101,731
A drug that belongs to a family of drugs called ribonucleotide reductase inhibitors.

MDX-010
A monoclonal antibody that is being studied in the treatment of metastatic melanoma and prostate, breast, and kidney cancer. Monoclonal antibodies are made in the laboratory and can locate and bind to cancer cells. MDX-010 binds to the molecule CTLA-4 on T cells and may help the immune system kill cancer cells.

MDX-060
A monoclonal antibody that is being studied in the treatment of some lymphomas. Monoclonal antibodies are produced in the laboratory and can locate and bind to cancer cells.

mean
A statistics term. The average value in a set of measurements. The mean is the sum of a set of numbers divided by how many numbers are in the set.

mean survival time
The average time that patients in a clinical study remained alive. The time is measured beginning either at diagnosis or the start of treatment.

measurable disease
A tumor that can be accurately measured in size. This information can be used to judge response to treatment.

mechlorethamine
A drug used to treat some types of cancer and some precancerous skin conditions. It belongs to the family of drugs called alkylating agents. Also called Mustargen.

MEDI-507
A monoclonal antibody that is being studied in the treatment of certain lymphoproliferative disorders and psoriasis. Also called siplizumab.

medial supraclavicular lymph node
A lymph node located above the collar bone and between the center of the body and a line drawn through the nipple to the shoulder.

median
A statistics term. The middle value in a set of measurements.

median survival time
The time from either diagnosis or treatment at which half of the patients with a given disease are found to be, or expected to be, still alive. In a clinical trial, median survival time is one way to measure how effective a treatment is.

mediastinal pleura
The thin membrane that lines the chest cavity in the area between the lungs.

mediastinoscopy (MEE-dee-as-tih-NOS-koh-pee)
A procedure in which a mediastinoscope is used to examine the organs in the area between the lungs and nearby lymph nodes. A mediastinoscope is a thin, tube-like instrument with a light and a lens for viewing. It may also have a tool to remove tissue to be checked under a microscope for signs of disease The mediastinoscope is inserted into the chest through an incision above the breastbone. This procedure is usually done to get a tissue sample from the lymph nodes on the right side of the chest.

mediastinum (mee-dee-a-STYE-num)
The area between the lungs. The organs in this area include the heart and its large blood vessels, the trachea, the esophagus, the bronchi, and lymph nodes.

medical castration
Refers to the use of drugs to suppress the function of the ovaries or testicles.

medical device (MEH-dih-kul dee-VICE)
An instrument, tool, machine, test kit, or implant that is used to prevent, diagnose, or treat disease or other conditions. Medical devices range from tongue depressors to heart pacemakers and medical imaging equipment.

medical nutrition therapy (MEH-dih-kul noo-TRIH-shun THAYR-uh-pee)
Treatment based on nutrition. It includes checking a person's nutrition status, and giving the right foods or nutrients to treat conditions such as those caused by diabetes, heart disease, and cancer. It may involve simple changes in a person's diet, or intravenous or tube feeding. Medical nutrition therapy may help patients recover more quickly and spend less time in the hospital. Also called nutrition therapy.

medical oncologist (MEH-dih-kul on-KOL-oh-jist)
A doctor who specializes in diagnosing and treating cancer using chemotherapy, hormonal therapy, and biological therapy. A medical oncologist often is the main health care provider for someone who has cancer. A medical oncologist also gives supportive care and may coordinate treatment given by other specialists.

medication (MEH-dih-KAY-shun)
A legal drug that is used to prevent, treat, or relieve symptoms of a disease or abnormal condition. Also called medicine.

medicine (MEH-dih-sin)
A legal drug that is used to prevent, treat, or relieve symptoms of a disease or abnormal condition. Also called medication.

medroxyprogesterone
A hormonal anticancer drug that is also used in cancer prevention. It belongs to the family of drugs called progestins.

medroxyprogesterone acetate
A drug used to prevent endometrial cancer. It is also used to treat menstrual disorders and as a form of birth control. It is a form of the female hormone progesterone and belongs to the family of drugs called progestins.

medullary breast carcinoma (MED-yoo-LAIR-ee...KAR-sih-NOH-muh)
A rare type of breast cancer that often can be treated successfully. It is marked by lymphocytes (a type of white blood cell) in and around the tumor that can be seen when viewed under a microscope.

medullary thyroid cancer (MED-yoo-LAIR-ee)
Cancer that develops in C cells of the thyroid. The C cells make a hormone (calcitonin) that helps maintain a healthy level of calcium in the blood.

medulloblastoma (MED-yoo-lo-blas-TOE-ma)
A malignant brain tumor that begins in the lower part of the brain and that can spread to the spine or to other parts of the body. Medulloblastomas are a type of primitive neuroectodermal tumor (PNET).

mega-voltage linear accelerator
MeV linear accelerator. A machine that uses electricity to form a stream of fast-moving subatomic particles. This creates high-energy radiation that may be used to treat cancer. Also called linear accelerator and linac.

Megace
A drug used to block estrogen and suppress the effects of estrogen and androgens. It is used to treat breast and endometrial cancer, and is being studied in the treatment of other types of cancer. It is also used to improve appetite in patients with cancer. Megace belongs to the group of hormones called progestins. Also called megestrol.

megestrol
A drug used to block estrogen and suppress the effects of estrogen and androgens. It is used to treat breast and endometrial cancer, and is being studied in the treatment of other types of cancer. It is also used to improve appetite in patients with cancer. Megestrol belongs to the group of hormones called progestins. Also called Megace.

meiosis
A special form of cell division in which each daughter cell receives half the amount of DNA as the parent cell. Meiosis occurs during formation of egg and sperm cells in mammals.

melanin (MEL-a-nin)
The substance that gives color to skin and eyes.

melanocyte (mel-AN-o-site)
A cell in the skin and eyes that produces and contains the pigment called melanin.

melanoma (MEH-luh-NOH-muh)
A form of skin cancer that begins in melanocytes (the cells that make the pigment melanin). Melanoma usually begins in a mole.

melanoma vaccine
A cancer vaccine prepared from human melanoma cancer cells. It can be used alone or with other therapy in treating melanoma.

melatonin (MEH-luh-TOH-nun)
A hormone made by the pineal gland (tiny organ near the center of the brain). Melatonin helps control the body's sleep cycle, and is an antioxidant. It is also made in the laboratory and sold as a supplement.

melphalan
A drug that is used to treat multiple myeloma and ovarian epithelial cancer and is being studied in the treatment of other types of cancer. It belongs to the family of drugs called alkylating agents. Also called Alkeran.

membrane
A very thin layer of tissue that covers a surface.

MEN-10755
An anticancer drug that belongs to the family of drugs called antitumor antibiotics.

MEN1 syndrome
Multiple endocrine neoplasia type 1 syndrome. A rare, inherited disorder that affects the endocrine glands and can cause tumors in the parathyroid and pituitary glands and the pancreas. These tumors (usually benign) cause the glands to secrete high levels of hormones, which can lead to other medical problems, such as kidney stones, fertility problems, and severe ulcers. In some cases, tumors inside the pancreas can become cancerous. Also called multiple endocrine adenomatosis and Wermer's syndrome.

meningeal
Refers to the meninges, the tissue covering the brain and spinal cord.

meningeal metastases
Cancer that has spread from the original (primary) tumor to the tissue covering the brain, spinal cord, or both.

meninges (meh-NIN-jeez)
The three membranes that cover and protect the brain and spinal cord.

meningioma (meh-nin-jee-O-ma)
A type of tumor that occurs in the meninges, the membranes that cover and protect the brain and spinal cord. Meningiomas usually grow slowly.

menopausal hormone therapy
Hormones (estrogen, progesterone, or both) given to women after menopause to replace the hormones no longer produced by the ovaries. Also called hormone replacement therapy or HRT.

menopause (MEN-uh-pawz)
The time of life when a woman's menstrual periods stop. A woman is in menopause when she hasn't had a period for 12 months in a row. Also called "change of life."

menorrhagia
Abnormally heavy menstrual bleeding.

menstrual cycle (MEN-stroo-al)
The monthly cycle of hormonal changes from the beginning of one menstrual period to the beginning of the next.

menstrual period (MEN-stroo-al PEER-ee-od)
The periodic discharge of blood and tissue from the uterus. From puberty until menopause, menstruation occurs about every 28 days, but does not occur during pregnancy.

menstruation (MEN-stroo-AY-shun)
Periodic discharge of blood and tissue from the uterus. From puberty until menopause, menstruation occurs about every 28 days when a woman is not pregnant.

mental health
A person's overall psychological and emotional condition. Good mental health is a state of well-being in which a person is able to cope with everyday events, think clearly, be responsible, meet challenges, and have good relationships with others.

mental health counselor
A specialist who can talk with patients and their families about emotional and personal matters, and can help them make decisions.

mercaptopurine
A drug used to treat acute lymphatic leukemia. It belongs to the family of drugs called antimetabolites. Also called Purinethol.

mercury
A silver-white, poisonous metal that is a liquid at ordinary temperatures. It is commonly used in thermometers and amalgams, and has been used as an ingredient in some homeopathic medicines and in very small amounts as a preservative in viral vaccines.

mercy killing
An easy or painless death, or the intentional ending of the life of a person suffering from an incurable or painful disease at his or her request. Also called euthanasia.

meridian (meh-RID-ee-un)
In traditional Chinese medicine, one of 20 channels that form a network through which qi (the body's vital energy) flows and that connect the body's acupuncture sites.

Merkel cell cancer
A rare type of cancer that forms on or just beneath the skin. Merkel cell cancer is divided into three types called trabecular, intermediate, and small cell.

mesenchymal
Refers to cells that develop into connective tissue, blood vessels, and lymphatic tissue.

mesenteric membrane
The peritoneal membrane that attaches the intestines to the abdominal wall near the back.

mesna
A drug that helps protect the kidneys and bladder from the toxic effects of anticancer drugs such as ifosfamide and cyclophosphamide.

mesonephroma
A rare type of tumor, usually of the female genital tract, in which the inside of the cells looks clear when viewed under a microscope. Also called clear cell carcinoma and clear cell adenocarcinoma.

mesothelioma
A benign (noncancerous) or malignant (cancerous) tumor affecting the lining of the chest or abdomen. Exposure to asbestos particles in the air increases the risk of developing malignant mesothelioma.

metabolic
Having to do with metabolism (the total of all chemical changes that take place in a cell or an organism to produce energy and basic materials needed for important life processes).

metabolic acidosis (met-ah-BOL-ik as-id-O-sis)
A condition in which the blood is too acidic. It may be caused by severe illness or sepsis (bacteria in the bloodstream).

metabolic disorder
A condition in which normal metabolic processes are disrupted, usually because of a missing enzyme.

metabolic therapy
Treatment to correct changes in metabolism that can be caused by disease.

metabolic type (MEH-tuh-BAH-lik tipe)
In alternative medicine, a theory that people fall into one of three groups (protein, carb, or mixed type) based on the main type of food that their bodies need to stay healthy.

metabolism
The total of all chemical changes that take place in a cell or an organism. These changes produce energy and basic materials needed for important life processes.

metabolite (meh-TA-boh-lite)
Any substance involved in metabolism (the chemical changes that take place in a cell or organism to make the energy and basic materials important in life processes). Metabolite is often used to describe the products left after a drug is used by the body.

metallic (meh-TA-lik)
Having to do with metal. Some cancer treatments may change the sense of taste and cause foods to have a metallic taste.

metaplasia
A change of cells to a form that does not normally occur in the tissue in which it is found.

metaplastic carcinoma
A general term used to describe cancer that begins in cells that have changed into another cell type (for example, a squamous cell of the esophagus changing to resemble a cell of the stomach). In some cases, metaplastic changes alone may mean there is an increased chance of cancer developing at the site.

metastasectomy (meh-TAS-ta-SEC-tuh-mee)
Surgery to remove one or more metastases (tumors formed from cells that have spread from the primary tumor). When all metastases are removed, it is called a complete metastasectomy.

metastasis (meh-TAS-ta-sis)
The spread of cancer from one part of the body to another. A tumor formed by cells that have spread is called a "metastatic tumor" or a "metastasis." The metastatic tumor contains cells that are like those in the original (primary) tumor. The plural form of metastasis is metastases (meh-TAS-ta-seez).

metastasize (meh-TAS-ta-size)
To spread from one part of the body to another. When cancer cells metastasize and form secondary tumors, the cells in the metastatic tumor are like those in the original (primary) tumor.

metastatic (MET-uh-STAT-ik)
Having to do with metastasis, which is the spread of cancer from one part of the body to another.

metastatic cancer
Cancer that has spread from the place in which it started to other parts of the body.

metasynchronous
Occurring at nearly the same time.

meteorism
Swelling of the abdomen caused by gas in the intestines or peritoneal cavity. Also called tympanites.

methodology (MEH-thuh-DAH-loh-jee)
In medicine, the rules and procedures for doing research and evaluating results.

methotrexate
A drug used to treat some types of cancers, including breast, head and neck, lung, blood, and bone, and other disorders. It belongs to the family of drugs called antimetabolites. Also called amethopterin.

methoxsalen (meh-THOX-uh-len)
A drug used together with UV light to treat psoriasis, vitiligo, and skin nodules of cutaneous T-cell lymphoma. It is also being studied in the treatment of graft-versus-host disease. It belongs to the family of drugs called psoralens and furocoumarins.

methoxypolyethylene glycol epoetin beta
A substance that is being studied in the treatment of anemia in patients who are receiving chemotherapy. It is a form of erythropoietin (a substance produced in the kidneys that stimulates the production of red blood cells) that has been changed in the laboratory. Also called Ro 50-3821.

methyl-5-aminolevulinate
A drug used in photodynamic therapy; it is absorbed by tumor cells and, when exposed to light, becomes active and kills the cancer cells.

methylphenidate
A drug that is a central nervous system stimulant.

methylprednisolone
A corticosteroid hormone replacement.

metoclopramide (met-oh-KLOH-pra-mide)
A drug that increases the motility (movements and contractions) of the stomach and upper intestine. It is used to treat certain stomach problems and nausea and vomiting caused by chemotherapy. It belongs to the families of drugs called antiemetics and motility agents. Also called Reglan.

metronidazole
A drug that is used to treat infection and is being studied in the treatment of cancer. It belongs to the families of drugs called antibacterials, antiprotozoals, and anthelmintics. Also called Flagyl.

metronomic therapy
Continuous or frequent treatment with low doses of anticancer drugs, often given with other methods of therapy.

Mexican valerian
Valeriana officinalis. A plant whose roots are used as a sedative and to treat certain medical conditions. It is being studied as a way to improve sleep in cancer patients undergoing treatment. Also called valerian, garden valerian, Indian valerian, Pacific valerian, garden heliotrope, and Valerianae radix.

MG98
An anticancer drug that belongs to the family of drugs called antisense compounds. These drugs interfere with production of certain proteins in the cell.

MGUS
Monoclonal gammopathy of undetermined significance. A benign condition in which there is a high level of a protein called M protein in the blood. Patients with MGUS are at an increased risk of developing cancer.

microcalcification (MY-krow-kal-si-fi-KAY-shun)
A tiny deposit of calcium in the breast that cannot be felt but can be detected on a mammogram. A cluster of these very small specks of calcium may indicate that cancer is present.

microgram
One millionth of a gram.

micrometastases
Small numbers of cancer cells that have spread from the primary tumor to other parts of the body and are too few to be picked up in a screening or diagnostic test.

micromolar (MY-kroh-MOH-lur)
A concentration of 1/1,000,000 (one millionth) molecular weight per liter (mol/L).

micronutrient (MY-kroh-NOO-tree-ent)
A substance the body needs in tiny amounts to grow and stay healthy. Examples are vitamins and minerals.

microorganism
An organism that can be seen only through a microscope. Microorganisms include bacteria, protozoa, algae, and fungi. Although viruses are not considered living organisms, they are sometimes classified as microorganisms.

microsatellite
A short sequence of DNA, usually 1 to 4 basepairs (a unit of DNA), that is repeated together in a row along the DNA molecule. There is variation from person to person in the number of repeats. There are hundreds of places in human DNA that contain microsatellites.

microsatellite instability
MSI. A change that occurs in the DNA of certain cells (such as tumor cells) in which the number of repeats of microsatellites (short, repeated sequences of DNA) is different than the number of repeats that was in the DNA when it was inherited. The cause of MSI may be a defect in the ability to repair mistakes made when DNA is copied in the cell.

microscopic
Too small to be seen without a microscope.

microstaging
A technique used to help determine the stage (extent) of melanoma and certain squamous cell cancers. A sample of skin that contains tumor tissue is examined under a microscope to find out how thick the tumor is and/or how deeply the tumor has grown into the skin or connective tissues.

microwave acupuncture (MY-kroh-WAYV AK-yoo-PUNK-cher)
A type of acupuncture in which a microwave device is attached to an acupuncture needle to give microwave radiation at an acupuncture point.

microwave therapy
A type of treatment in which body tissue is exposed to high temperatures to damage and kill cancer cells or to make cancer cells more sensitive to the effects of radiation and certain anticancer drugs. Also called microwave thermotherapy.

microwave thermotherapy
A type of treatment in which body tissue is exposed to high temperatures to damage and kill cancer cells or to make cancer cells more sensitive to the effects of radiation and certain anticancer drugs. Also called microwave therapy.

mifepristone
An anticancer drug that blocks the action of progesterone, a hormone that affects the growth of some cancers.

milk thistle
A plant that has been used in some cultures to treat certain medical problems, including stomach, liver, and gallbladder disorders. The active extract of milk thistle seeds is called silymarin. It is being studied in the prevention of liver damage caused by some cancer treatments. Also called Silybum marianum.

milligram
A measure of weight. A milligram is approximately 450,000 times smaller than a pound and 28,000 times smaller than an ounce.

milliliter
A measure of volume for a liquid. A milliliter is approximately 950 times smaller than a quart and 30 times smaller than a fluid ounce. A milliliter of liquid and a cubic centimeter (cc) of liquid are the same.

millimeter
A measure of length in the metric system. A millimeter is one thousandth of a meter. There are 25 millimeters in an inch.

mind/body exercise (mind BAH-dee EK-ser-SIZE)
A form of exercise that combines body movement with mental focus and controlled breathing to improve strength, balance, flexibility, and overall health. Examples of mind/body exercises are yoga, tai chi, and qigong.

mindfulness relaxation
A type of meditation based on the concept of being "mindful," or having increased awareness, of the present. It uses breathing methods, guided imagery, and other practices to relax the body and mind and help reduce stress.

mineral
A nutrient required to maintain health.

Miraluma test
A type of breast imaging test that is used to detect cancer cells in the breasts of some women who have had abnormal mammograms, or who have dense breast tissue. The Miraluma test is not used for screening, or in place of a mammogram. In this test, a woman receives an injection of a small amount of a radioactive substance called technetium 99, which is taken up by cancer cells, and a gamma camera is used to take pictures of the breasts. Also called scintimammography and sestamibi breast imaging.

mirtazapine (mir-TAZ-a-peen)
A drug used to treat depression. It belongs to the family of drugs called antidepressant agents. Also called Remeron.

misoprostol
A radioprotective agent that belongs to the family of drugs called prostaglandins.

mistletoe
A semiparasitic plant that grows on some types of trees. Mistletoe extracts are being studied as treatments for cancer.

mistletoe lectin
A substance that comes from the mistletoe plant and that is being studied as a treatment for cancer. A lectin is a complex molecule that has both protein and sugars. Lectins are able to bind to the outside of a cell and cause biochemical changes in it. Lectins are made by both animals and plants.

Mithracin (MITH-ruh-sin)
A drug used to treat some types of testicular cancer, hypercalcemia (abnormally high levels of calcium in the blood), and hypercalciuria (abnormally high levels of calcium in the urine). It belongs to the families of drugs called antineoplastics and antibiotics. Also called plicamycin.

mitigate
To make milder or less painful.

mitochondria
Parts of a cell where aerobic production (also called cell respiration) takes place.

mitolactol
An anticancer drug that belongs to the family of drugs called alkylating agents.

mitomycin
An anticancer drug that belongs to the family of drugs called antitumor antibiotics.

mitosis
The process of division of somatic cells in which each daughter cell receives the same amount of DNA as the parent cell.

mitotane
An anticancer drug used in treating adrenocortical cancer and ACTH-producing pituitary tumors (Cushing's disease).

mitotic activity
Having to do with the presence of dividing (proliferating) cells. Cancerous tissue generally has more mitotic activity than normal tissues.

mitotic index
In a population of cells, the ratio of the number of cells undergoing mitosis (cell division) to the number of cells not undergoing mitosis.

mitotic inhibitor
A drug that inhibits cell growth by stopping cell division. Mitotic inhibitors are used as treatments for cancer. Also called antimitotic or antimicrotubule agents and taxanes. Docetaxel and paclitaxel are mitotic inhibitors.

mitoxantrone
A drug used to treat advanced prostate cancer that does not respond to hormones, adult acute nonlymphocytic leukemia, and advanced or chronic multiple sclerosis. It is also being studied in the treatment of other cancers. It belongs to the family of drugs called antitumor antibiotics. Also called Novantrone.

mivobulin isethionate
An anticancer drug that belongs to the family of drugs called mitotic inhibitors. Also called CI-980.

mixed glioma
A brain tumor that occurs in more than one type of brain cell, including astrocytes, ependymal cells, and oligodendrocytes.

MLN2704
A substance that is being studied as a treatment for prostate cancer. It belongs to the family of drugs called antibody conjugates.

modafinil
A drug that is being studied as a treatment for fatigue in patients with cancer. It belongs to the family of drugs called stimulants.

modality
A method of treatment. For example, surgery and chemotherapy are treatment modalities.

modified radical mastectomy (mas-TEK-toe-mee)
Surgery for breast cancer in which the breast, most or all of the lymph nodes under the arm, and the lining over the chest muscles are removed. Sometimes the surgeon also removes part of the chest wall muscles.

modulate
To adjust, or change.

Mohs micrographic surgery
A surgical procedure used to treat skin cancer. Individual layers of cancerous tissue are removed and examined under a microscope one at a time until all cancerous tissue has been removed. Also called Mohs surgery.

Mohs surgery (MOZE SER-juh-ree)
A surgical procedure used to treat skin cancer. Individual layers of cancerous tissue are removed and examined under a microscope one at a time until all cancerous tissue has been removed. Also called Mohs micrographic surgery.

molar pregnancy
A condition in women of childbearing age in which grape-like cysts grow in the uterus after conception (fertilization of an egg by a sperm). Molar pregnancies may change into a type of cancer called choriocarcinoma or gestational trophoblastic tumor. Also called hydatidiform mole.

mold
A form of fungus. Some molds can cause disease in humans.

mole (mohl)
In medicine, a benign growth on the skin that is formed by a cluster of melanocytes (cells that make the pigment melanin). Moles are usually dark, and may be raised from the skin.

molecular mass
The sum of the atomic masses of all atoms in a molecule, based on a scale in which the atomic masses of hydrogen, carbon, nitrogen, and oxygen are 1, 12, 14, and 16, respectively. For example, the molecular mass of water, which has two atoms of hydrogen and one atom of oxygen, is 18 (i.e., 2 + 16).

molecular risk assessment
A procedure in which biomarkers (for example, biological molecules or changes in tumor cell DNA) are used to estimate a person's risk for developing cancer. Specific biomarkers may be linked to particular types of cancer.

molecularly targeted therapy
In cancer treatment, substances that kill cancer cells by targeting key molecules involved in cancer cell growth.

molecule
The smallest particle of a substance that has all of the physical and chemical properties of that substance. Molecules are made up of one or more atoms. If they contain more than one atom, the atoms can be the same (an oxygen molecule has two oxygen atoms) or different (a water molecule has two hydrogen atoms and one oxygen atom). Biological molecules, such as proteins and DNA, can be made up of many thousands of atoms.

monoclonal antibody (MAH-no-KLO-nul AN-tih-BAH-dee)
A laboratory-produced substance that can locate and bind to cancer cells wherever they are in the body. Many monoclonal antibodies are used in cancer detection or therapy; each one recognizes a different protein on certain cancer cells. Monoclonal antibodies can be used alone, or they can be used to deliver drugs, toxins, or radioactive material directly to a tumor.

monoclonal gammopathy of undetermined significance
MGUS. A benign condition in which there is a high level of a protein called M protein in the blood. Patients with MGUS are at an increased risk of developing cancer.

monoclonal protein
An antibody or part of an antibody found in unusually large amounts in the blood or urine of people with multiple myeloma and other types of plasma cell tumors. Also called M protein.

monocyte
A type of white blood cell.

Montanide ISA-51
A drug used in vaccine therapy to stimulate the immune system.

morbidity
A disease or the incidence of disease within a population. Morbidity also refers to adverse effects caused by a treatment.

Morinda citrifolia
A tropical shrub. An extract from the fruit is being studied as a treatment for cancer, and extracts from the fruit, leaves, or roots have been used in some cultures to treat other diseases. Also called noni.

morphine
A narcotic drug used in the treatment of pain.

morphology
The science of the form and structure of organisms (plants, animals, and other forms of life).

motexafin gadolinium
A substance that is being studied in the treatment of cancer. It may make tumor cells more sensitive to radiation therapy, improve tumor images using magnetic resonance imaging (MRI), and kill cancer cells. It belongs to the family of drugs called metalloporphyrin complexes. Also called gadolinium texaphyrin.

motexafin lutetium
A substance that is being studied in the treatment of cancer using photodynamic therapy. It belongs to the family of drugs called metallotexaphyrins. Also called lutetium texaphyrin.

motor
In medicine, having to do with the movement of body parts.

moxibustion (MOK-sih-BUS-chun)
In traditional Chinese medicine, a type of heat therapy in which an herb is burned on or above the skin to warm and stimulate an acupuncture point or affected area.

moxifloxacin
A drug used to treat bacterial infections. It belongs to the family of drugs called fluoroquinolone antibiotics.

MPNST
Malignant peripheral nerve sheath tumor. A type of soft tissue sarcoma that develops in cells that form a protective sheath (covering) around peripheral nerves, which are nerves that are outside of the central nervous system (brain and spinal cord).

MRI
Magnetic resonance imaging (mag-NET-ik REZ-o-nans IM-a-jing). A procedure in which radio waves and a powerful magnet linked to a computer are used to create detailed pictures of areas inside the body. These pictures can show the difference between normal and diseased tissue. MRI makes better images of organs and soft tissue than other scanning techniques, such as CT or x-ray. MRI is especially useful for imaging the brain, spine, the soft tissue of joints, and the inside of bones. Also called nuclear magnetic resonance imaging (NMRI).

MRSI
Magnetic resonance spectroscopic imaging. A noninvasive imaging method that provides information about cellular activity (metabolic information). It is used along with magnetic resonance imaging (MRI) which provides information about the shape and size of the tumor (spacial information).

MS 209
A substance that is being studied for its ability to make cancer cells respond better to chemotherapy drugs to which they have become resistant. It belongs to the family of drugs called quinolone antibiotics.

MS-275
A substance that is being studied in the treatment of cancers of the blood. It belongs to the family of drugs called histone deacetylase inhibitors.

mucin/peptide
A protein/sugar compound made by some cancer cells.

mucinous (MYOO-sin-us)
Containing or resembling mucin, the main compound in mucus.

mucinous carcinoma (MYOO-sin-us KAR-sih-NOH-muh)
A type of cancer that begins in cells that line certain internal organs and produce mucin (the main component of mucus).

mucosa (myoo-KOH-suh)
The moist, inner lining of some organs and body cavities (such as the nose, mouth, lungs, and stomach). Glands in the mucosa make mucus (a thick, slippery fluid). Also called mucous membrane.

mucosa-associated lymphoid tissue lymphoma
MALT lymphoma. A type of cancer that arises in cells in mucosal tissue that are involved in antibody production.

mucositis
A complication of some cancer therapies in which the lining of the digestive system becomes inflamed. Often seen as sores in the mouth.

mucous membrane (MYOO-kus...)
The moist, inner lining of some organs and body cavities (such as the nose, mouth, lungs, and stomach). Glands in the mucous membrane make mucus (a thick, slippery fluid). Also called mucosa.

mucus (MYOO-kus)
A thick, slippery fluid made by the membranes that line certain organs of the body, including the nose, mouth, throat, and vagina.

muJ591
A type of monoclonal antibody used in cancer detection or therapy. Monoclonal antibodies are laboratory-produced substances that can locate and bind to cancer cells.

Mullerian tumor (myoo-LER-ee-un...)
A rare cancer of the uterus, ovary, or fallopian tubes.

multicenter study
A clinical trial that is carried out at more than one medical institution.

multicentric breast cancer (mul-tee-SEN-trik)
Breast cancer in which there is more than one tumor, all of which have formed separately from one another. The tumors are likely to be in different quadrants (sections) of the breast. Multicentric breast cancers are rare.

multidisciplinary
In medicine, a term used to describe a treatment planning approach or team that includes a number of doctors and other health care professionals who are experts in different specialties (disciplines). In cancer treatment, the primary disciplines are medical oncology (treatment with drugs), surgical oncology (treatment with surgery), and radiation oncology (treatment with radiation).

multidisciplinary opinion
A treatment planning approach in which a number of doctors who are experts in different specialties (disciplines) review and discuss the medical condition and treatment options of a patient. In cancer treatment, a multidisciplinary opinion may include that of a medical oncologist (who provides cancer treatment with drugs), a surgical oncologist (who provides cancer treatment with surgery), and a radiation oncologist (who provides cancer treatment with radiation). Also called a tumor board review.

multidrug resistance
Adaptation of tumor cells to anticancer drugs in ways that make the drugs less effective.

multidrug resistance inhibition
Treatment used to make cancer cells less resistant to anticancer drugs.

multifocal breast cancer (mul-tee-FO-kal)
Breast cancer in which there is more than one tumor, all of which have arisen from one original tumor. The tumors are likely to be in the same quadrant (section) of the breast.

multimodality treatment
Therapy that combines more than one method of treatment.

multiple endocrine adenomatosis
A rare, inherited disorder that affects the endocrine glands and can cause tumors in the parathyroid and pituitary glands and the pancreas. These tumors (usually benign) cause the glands to secrete high levels of hormones, which can lead to other medical problems, such as kidney stones, fertility problems, and severe ulcers. In some cases, tumors inside the pancreas can become cancerous. Also called multiple endocrine neoplasia type 1 syndrome and Wermer's syndrome.

multiple endocrine neoplasia syndrome
An inherited tendency to develop thyroid cancer and other cancers of the endocrine system. The altered gene can be detected with a blood test.

multiple endocrine neoplasia type 1 syndrome
MEN1 syndrome. A rare, inherited disorder that affects the endocrine glands and can cause tumors in the parathyroid and pituitary glands and the pancreas. These tumors (usually benign) cause the glands to secrete high levels of hormones, which can lead to other medical problems, such as kidney stones, fertility problems, and severe ulcers. In some cases, tumors inside the pancreas can become cancerous. Also called multiple endocrine adenomatosis and Wermer's syndrome.

multiple myeloma (my-eh-LOW-ma)
A type of cancer that begins in plasma cells (white blood cells that produce antibodies). Also called Kahler's disease, myelomatosis, or plasma cell myeloma.

multiple sclerosis
A disorder of the central nervous system marked by weakness, numbness, a loss of muscle coordination, and problems with vision, speech, and bladder control. Multiple sclerosis is thought to be an autoimmune disease in which the body's immune system destroys myelin. Myelin is a substance that contains both protein and fat (lipid), serving as a nerve insulator and helping in the transmission of nerve signals.

multiplicity
A large number or variety.

mung bean
A type of bean grown in warm climates, usually for its seed and for bean sprouts. Mung bean may have anticancer effects.

muromonab-CD3
A type of monoclonal antibody used in cancer detection or therapy. Monoclonal antibodies are laboratory-produced substances that can locate and bind to cancer cells.

muscle wasting (MUH-sul WAY-sting)
A weakening, shrinking, and loss of muscle caused by disease or lack of use. Muscle wasting decreases strength and the ability to move.

musculoskeletal
Having to do with muscles, bones, and cartilage.

Mustargen
A drug used to treat some types of cancer and some precancerous skin conditions. It belongs to the family of drugs called alkylating agents. Also called mechlorethamine.

mutate
To change the genetic material of a cell. The changes (mutations) can be harmful, beneficial, or have no effect.

mutation
Any change in the DNA of a cell. Mutations may be caused by mistakes during cell division, or they may be caused by exposure to DNA-damaging agents in the environment. Mutations can be harmful, beneficial, or have no effect. If they occur in cells that make eggs or sperm, they can be inherited; if mutations occur in other types of cells, they are not inherited. Certain mutations may lead to cancer or other diseases.

myalgia (my-AL-juh)
Pain in a muscle or group of muscles.

myasthenia gravis (MY-us-THEE-nee-uh GRA-vis)
A disease in which antibodies made by a person's immune system prevent certain nerve-muscle interactions. It causes weakness in the arms and legs, vision problems, and drooping eyelids or head. It may also cause paralysis and problems with swallowing, talking, climbing stairs, lifting things, and getting up from a sitting position. The muscle weakness gets worse during activity, and improves after periods of rest.

mycophenolate mofetil
A drug that is being studied for its effectiveness in preventing graft-versus-host disease and autoimmune disorders.

mycosis fungoides (my-KOH-sis fun-GOY-deez)
A type of non-Hodgkin's lymphoma that first appears on the skin and can spread to the lymph nodes or other organs such as the spleen, liver, or lungs.

mycosis fungoides plaque (my-KOH-sis fun-GOY-deez plak)
In mycosis fungoides, an area of skin that is thickened, raised, red, scaly, and itchy.

mycostatin
A drug that treats infections caused by fungi.

myelin (MY-eh-lin)
The fatty substance that covers and protects nerves.

myeloablation
A severe form of myelosuppression. Myelosuppression is a condition in which bone marrow activity is decreased, resulting in fewer red blood cells, white blood cells, and platelets. It is a side effect of some cancer treatments.

myelodysplasia
Abnormal bone marrow cells that may lead to myelogenous leukemia.

myelodysplastic syndrome (MYE-eh-lo-dis-PLAS-tik SIN-drome)
Disease in which the bone marrow does not function normally. Also called preleukemia or smoldering leukemia.

myelofibrosis
A disorder in which the bone marrow is replaced by fibrous tissue.

myelogenous (my-eh-LAH-jen-us)
Having to do with, produced by, or resembling the bone marrow. Sometimes used as a synonym for myeloid; for example, acute myeloid leukemia and acute myelogenous leukemia are the same disease.

myelogram (MY-eh-lo-gram)
An x-ray of the spinal cord after an injection of dye into the space between the lining of the spinal cord and brain.

myeloid (MY-eh-loyd)
Having to do with or resembling the bone marrow. May also refer to certain types of hematopoietic (blood-forming) cells found in the bone marrow. Sometimes used as a synonym for myelogenous; for example, acute myeloid leukemia and acute myelogenous leukemia are the same disease.

myeloma
Cancer that arises in plasma cells, a type of white blood cell.

myelomatosis
A type of cancer that begins in plasma cells (white blood cells that produce antibodies). Also called multiple myeloma, Kahler's disease, or plasma cell myeloma.

myelomonocyte (MY-eh-loh-MON-oh-site)
An abnormal type of white blood cell that is found in chronic myelomonocytic leukemia. These cells are similar to both monocytes and myelocytes (immature cells that develop into different types of immune system cells).

myeloproliferative disorder
A disease in which too many blood cells are made in the bone marrow.

myelosclerosis with myeloid metaplasia
A progressive, chronic disease in which the bone marrow is replaced by fibrous tissue and blood is made in organs such as the liver and the spleen, instead of in the bone marrow. This disease is marked by an enlarged spleen and progressive anemia. Also called chronic idiopathic myelofibrosis, agnogenic myeloid metaplasia, primary myelofibrosis, and idiopathic myelofibrosis.

myelosuppression
A condition in which bone marrow activity is decreased, resulting in fewer red blood cells, white blood cells, and platelets. Myelosuppression is a side effect of some cancer treatments. When myelosuppression is severe, it is called myeloablation.

myelosuppressive therapy
Treatment that inhibits blood cell production.

myometrium (mye-o-MEE-tree-um)
The muscular outer layer of the uterus.

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N-acetylcysteine
An antioxidant drug that may keep cancer cells from developing or reduce the risk of growth of existing cancer.

N-acetyldinaline
A substance that is being studied as an anticancer drug in the treatment of non-small cell lung cancer. Also called CI-994.

N-butyl-N-(4-hydroxybutyl) nitrosamine
A substance that is used in cancer research to cause bladder tumors in laboratory animals. This is done to test new diets, drugs, and procedures for use in cancer prevention and treatment.

NaCl
Chemical abbreviation for sodium chloride (table salt).

naloxone
A substance that is being studied as a treatment for constipation caused by narcotic medications. It belongs to the family of drugs called narcotic antagonists.

nanogram
A measure of weight. One nanogram weighs a billion times less than one gram, and almost a trillion-times less than a pound.

nanotechnology (NA-noh-tek-NAH-luh-jee)
The field of research that deals with the engineering and creation of things from materials that are less than 100 nanometers (one-billionth of a meter) in size, especially single atoms or molecules. Nanotechnology is being studied in the detection, diagnosis, and treatment of cancer.

narcotic
An agent that causes insensibility or stupor; usually refers to opioids given to relieve pain.

nasal
By or having to do with the nose.

nasopharyngeal cancer (NA-zoh-fuh-RIN-jee-ul KAN-ser)
Cancer that forms in tissues of the nasopharynx (upper part of the throat behind the nose). Most nasopharyngeal cancers are squamous cell carcinomas (cancer that begins in flat cells lining the nasopharynx).

nasopharynx (NA-zoh-fayr-inx)
The upper part of the throat behind the nose. An opening on each side of the nasopharynx leads into the ear.

nasoscope (NAY-zoh-skope)
A thin tube-like instrument used to examine the inside of the nose. A nasoscope has a light and a lens for viewing and may have a tool to remove tissue. Also called a rhinoscope

nasoscopy (nay-ZOS-koh-pee)
Examination of the inside of the nose using a nasoscope. A nasoscope is a thin, tube-like instrument with a light and a lens for viewing. It may also have a tool to remove tissue to be checked under a microscope for signs of disease. Also called rhinoscopy.

National Cancer Institute
NCI. The National Cancer Institute, part of the National Institutes of Health of the United States Department of Health and Human Services, is the Federal Government's principal agency for cancer research. NCI conducts, coordinates, and funds cancer research, training, health information dissemination, and other programs with respect to the cause, diagnosis, prevention, and treatment of cancer. Access the NCI Web site at http://cancer.gov.

National Center for Complementary and Alternative Medicine
NCCAM. A federal agency that uses science to explore CAM practices, trains CAM researchers, and provides authoritative information about CAM to professionals and the public. NCCAM awards grants for research projects, training, and career development in CAM; sponsors conferences, educational programs, and exhibits; studies ways to use proven CAM practices along with conventional medical practice; and supports adding CAM to medical, dental, and nursing school programs. NCCAM is part of the National Institutes of Health.

National Institutes of Health
NIH. The National Institutes of Health, the focal point of biomedical research in the United States, conducts research in its own laboratories; supports the research of non-Federal scientists in universities, medical schools, hospitals, and research institutions throughout the country and abroad; helps in the training of research investigators; and fosters communication of medical information. Access the NIH Web site at http://www.nih.gov.

natural killer cell
NK cell. A type of white blood cell that contains granules with enzymes that can kill tumor cells or microbial cells. Also called a large granular lymphocyte.

nausea
A feeling of sickness or discomfort in the stomach that may come with an urge to vomit. Nausea is a side effect of some types of cancer therapy.

NB1011
A substance that is being studied for its ability to make cancer cells respond to drugs to which they have become resistant. It belongs to the family of drugs called nucleoside analogs.

NBI-3001
A substance that is being studied in the treatment of cancer. It is made by combining interleukin 4 with a bacterial toxin, and belongs to the family of drugs called recombinant chimeric proteins. Also called interleukin-4 PE38KDEL immunotoxin and interleukin-4 PE38KDEL cytotoxin.

NCCAM
National Center for Complementary and Alternative Medicine. A federal agency that uses science to explore CAM practices, trains CAM researchers, and provides authoritative information about CAM to professionals and the public. NCCAM awards grants for research projects, training, and career development in CAM; sponsors conferences, educational programs, and exhibits; studies ways to use proven CAM practices along with conventional medical practice; and supports adding CAM to medical, dental, and nursing school programs. NCCAM is part of the National Institutes of Health.

NCI
National Cancer Institute. NCI, part of the National Institutes of Health of the United States Department of Health and Human Services, is the Federal Government's principal agency for cancer research. NCI conducts, coordinates, and funds cancer research, training, health information dissemination, and other programs with respect to the cause, diagnosis, prevention, and treatment of cancer. Access the NCI Web site at http://cancer.gov.

NCI clinical trials cooperative group (...koh-OP-uh-ruh-tiv GROOP)
A group of researchers, cancer centers, and community doctors who are involved in studies of new cancer treatment, prevention, early detection, quality of life, and rehabilitation. Clinical trials carried out by cooperative groups are sponsored by NCI, and large numbers of patients take part in many locations. Examples include the Radiation Therapy Oncology Group (RTOG), Gynecologic Oncology Group (GOG), and Children's Oncology Group (COG).

NDV
Newcastle disease virus. A bird virus that is being studied in the treatment of cancer. It may be used to kill cancer cells directly, or it may be given as a cancer vaccine to stimulate the body's immune system. NDV belongs to the families of drugs called biological response modifiers and vaccine therapy.

nebulizer
A device used to turn liquid into a fine spray.

neck dissection (dye-SEK-shun)
Surgery to remove lymph nodes and other tissues in the neck.

necrosis (ne-KRO-sis)
Refers to the death of living tissues.

needle biopsy
The removal of tissue or fluid with a needle for examination under a microscope. Also called fine-needle aspiration.

needle-localized biopsy
A procedure that uses very thin needles or guide wires to mark the location of an abnormal area of tissue so it can be surgically removed. An imaging device is used to place the wire in or around the abnormal area. Needle localization is used when the doctor cannot feel the mass of abnormal tissue.

needling (NEE-dul-ing)
In acupuncture, the insertion of a thin needle into a specific place on the body to unlock qi (vital energy). The needle may be twirled, moved up and down at different speeds and depths, heated, or charged with a low electric current.

nefazodone (nef-AY-zoh-done)
A drug used to treat depression. It belongs to the family of drugs called antidepressant agents. Also called Serzone.

negative axillary lymph node
A lymph node in the armpit that is free of cancer.

negative test result
A test result that fails to show the specific disease or condition for which the test was being done.

nelarabine
A substance that is being studied in the treatment of cancer. It belongs to the family of drugs called antimetabolites. Also called 506U78.

nelfinavir mesylate
A drug that interferes with the ability of a virus to make copies of itself.

neoadjuvant therapy (NEE-o-AD-joo-vant)
Treatment given before the primary treatment. Examples of neoadjuvant therapy include chemotherapy, radiation therapy, and hormone therapy.

neoplasia (NEE-o-PLAY-zha)
Abnormal and uncontrolled cell growth.

neoplasm
An abnormal mass of tissue that results when cells divide more than they should or do not die when they should. Tumors may be benign (not cancerous), or malignant (cancerous). Also called tumor.

neoplastic meningitis
A condition in which cancer cells spread into the meninges (membranes that surround the brain and spinal cord).

nephrectomy (neh-FREK-tuh-mee)
Surgery to remove a kidney or part of a kidney. In a partial nephrectomy, part of one kidney or a tumor is removed, but not an entire kidney. In a simple nephrectomy, one kidney is removed. In a radical nephrectomy, an entire kidney, nearby adrenal gland and lymph nodes, and other surrounding tissue are removed. In a bilateral nephrectomy, both kidneys are removed.

nephrologist (neh-FROL-uh-jist)
A doctor who specializes in diagnosing and treating kidney disease.

nephrostomy (neh-FROS-tuh-mee)
Surgery to make an opening from the outside of the body to the renal pelvis (part of the kidney that collects urine). This may be done to drain urine from a blocked kidney or blocked ureter into a bag outside the body. It may also be done to look at the kidney using an endoscope (thin, lighted tube attached to a camera), to place anticancer drugs directly into the kidney, or to remove kidney stones.

nephrotomogram (nef-ro-TOE-mo-gram)
A series of x-rays of the kidneys. The x-rays are taken from different angles and show the kidneys clearly, without the shadows of the organs around them.

nephrotoxic
Poisonous or damaging to the kidney.

nephroureterectomy
Surgery to remove a kidney and its ureter. Also called ureteronephrectomy.

nerve
A bundle of fibers that receives and sends messages between the body and the brain. The messages are sent by chemical and electrical changes in the cells that make up the nerves.

nerve block
A procedure in which medicine is injected directly into or around a nerve or into the spine to block pain.

nerve cell
A type of cell that receives and sends messages from the body to the brain and back to the body. The messages are sent by a weak electrical current. Also called a neuron.

nerve grafting
Replacing a damaged nerve with a section of a healthy nerve that has been removed from another part of the body. This procedure is being studied in the prevention of erectile dysfunction in men having surgery for prostate cancer.

nerve growth factor (nurv grohth FAK-ter)
A protein made by the body that causes certain nerve cells to grow and helps keep them alive.

nerve-sparing radical prostatectomy
Surgery to remove the prostate in which an attempt is made to save the nerves that help cause penile erections.

nerve-sparing surgery (SER-juh-ree)
A type of surgery that attempts to save the nerves near the tissues being removed.

nervous system (NER-vuss SISS-tum)
The organized network of nerve tissue in the body. It includes the central nervous system (the brain and spinal cord), the peripheral nervous system (nerves that extend from the spinal cord to the rest of the body), and other nerve tissue.

Neulasta (noo-LA-stuh)
A drug used to increase numbers of white blood cells in patients who are receiving chemotherapy. It belongs to the family of drugs called colony-stimulating factors. Also called pegfilgrastim and filgrastim-SD/01.

neural
Having to do with nerves or the nervous system, including the brain and the spinal cord.

neuro-oncologist (NOO-ro-on-KOL-o-jist)
A doctor who specializes in diagnosing and treating brain tumors and other tumors of the nervous system.

neurobehavioral
Having to do with the way the brain affects emotion, behavior, and learning. Some cancers or their treatment may cause neurobehavioral problems.

neuroblastoma
Cancer that arises in immature nerve cells and affects mostly infants and children.

neurocognitive
Having to do with the ability to think and reason. This includes the ability to concentrate, remember things, process information, learn, speak, and understand.

neuroectodermal tumor (NOOR-oh-EK-toh-DER-mul TOO-mer)
A tumor of the central or peripheral nervous system.

neuroendocrine (NOO-ro-EN-do-krin)
Having to do with the interactions between the nervous system and the endocrine system. Neuroendocrine describes certain cells that release hormones into the blood in response to stimulation of the nervous system.

neuroendocrine tumor
A tumor derived from cells that release a hormone in response to a signal from the nervous system. Some examples of neuroendocrine tumors are carcinoid tumors, islet cell tumors, medullary thyroid carcinoma, and pheochromocytoma. These tumors secrete hormones in excess, causing a variety of symptoms.

neuroepithelial
Having to do with tissue made up of sensory cells, such as tissue found in the ear, nose, and tongue.

neurofibroma
A benign tumor that develops from the cells and tissues that cover nerves.

neurofibromatosis type 1
NF1. A rare genetic condition that causes brown spots and tumors on the skin, freckling in skin areas not exposed to the sun, tumors on the nerves, and developmental changes in the nervous system, muscles, bone, and skin.

neurofibromatosis type 2
NF2. A genetic condition in which tumors form on the nerves of the inner ear and cause loss of hearing and balance. Tumors may also occur in the brain and on nerves in the skull and spinal cord, and may cause loss of speech, eye movement, and the ability to swallow. Also called acoustic neurofibromatosis.

neuroleptic malignant syndrome (NOOR-oh-LEP-tik muh-LIG-nunt SIN-drome)
NMS. A life-threatening condition that may be caused by certain drugs used to treat mental illness, nausea, or vomiting. Symptoms include high fever, sweating, unstable blood pressure, confusion, and stiffness.

neurologic (noor-uh-LOJ-ik)
Having to do with nerves or the nervous system.

neurological exam
A series of questions and tests to check brain, spinal cord, and nerve function. The exam checks a person's mental status, coordination, ability to walk, and how well the muscles, sensory systems, and deep tendon reflexes work.

neurologist (noo-ROL-o-jist)
A doctor who specializes in the diagnosis and treatment of disorders of the nervous system.

neuroma (noo-RO-ma)
A tumor that arises in nerve cells.

neuron
A type of cell that receives and sends messages from the body to the brain and back to the body. The messages are sent by a weak electrical current. Also called a nerve cell.

neuropathologist
A pathologist who specializes in diseases of the nervous system. A pathologist identifies disease by studying cells and tissues under a microscope.

neuropathy
A problem in peripheral nerve function (any part of the nervous system except the brain and spinal cord) that causes pain, numbness, tingling, swelling, and muscle weakness in various parts of the body. Neuropathies may be caused by physical injury, infection, toxic substances, disease (e.g., cancer, diabetes, kidney failure, or malnutrition), or drugs such as anticancer drugs. Also called peripheral neuropathy.

neuropeptide
A member of a class of protein-like molecules made in the brain. Neuropeptides consist of short chains of amino acids, with some functioning as neurotransmitters and some functioning as hormones.

neuropsychology (NOOR-oh-sy-KAH-loh-jee)
The study of how the brain and central nervous system are related to behavior.

neuroradiologist
A doctor trained in radiology who specializes in creating and interpreting pictures of the nervous system. The pictures are produced using forms of radiation, such as x-rays, sound waves, or other types of energy.

neurosurgeon (NOO-ro-SER-jun)
A doctor who specializes in surgery on the brain, spine, and other parts of the nervous system.

neurotoxicity
The tendency of some treatments to cause damage to the nervous system.

neurotoxin
A substance that is poisonous to nerve tissue.

neurotransmitter (NOOR-oh-tranz-MIH-ter)
A chemical that is made by nerve cells and used to communicate with other cells, including other nerve cells and muscle cells.

neurotropism
An ability to invade and live in neural tissue. This term is usually used to describe the ability of viruses to infect nerve tissue.

neutropenia
An abnormal decrease in the number of neutrophils, a type of white blood cell.

neutrophil (NOO-tro-fil)
A type of white blood cell.

nevoid basal cell carcinoma syndrome (NEE-voyd BAY-sul cell KAR-sih-NOH-muh...)
A genetic condition that causes unusual facial features and disorders of the skin, bones, nervous system, eyes, and endocrine glands. People with this syndrome have a higher risk of basal cell carcinoma. Also called Gorlin syndrome and basal cell nevus syndrome.

nevus (NEE-vus)
A benign growth on the skin, such as a mole. A mole is a cluster of melanocytes and surrounding supportive tissue that usually appears as a tan, brown, or flesh-colored spot on the skin. The plural of nevus is nevi (NEE-vye).

Newcastle disease virus
NDV. A bird virus that is being studied in the treatment of cancer. It may be used to kill cancer cells directly, or it may be given as a cancer vaccine to stimulate the body's immune system. Newcastle disease virus belongs to the families of drugs called biological response modifiers and vaccine therapy.

Nexavar (NEX-a-var)
A drug used to treat advanced kidney cancer. It belongs to the families of drugs called Raf kinase inhibitors and VEGF receptor kinase inhibitors. Also called BAY 43-9006 and sorafenib.

NF1
Neurofibromatosis type 1. A rare genetic condition that causes brown spots and tumors on the skin, freckling in skin areas not exposed to the sun, tumors on the nerves, and developmental changes in the nervous system, muscles, bone, and skin.

NG-monomethyl-L-arginine
An amino acid derivative used to counteract high blood pressure caused by interleukin-2.

NGR-TNF
A substance that is being studied in the treatment of cancer. It is made by linking tumor necrosis factor (TNF) to a peptide. The peptide binds to tumor blood vessels, and TNF damages them. It belongs to the family of drugs called biological response modifiers. Also called tumor vasculature-targeted tumor necrosis factor alpha.

NHL
Non-Hodgkin's lymphoma. Any of a large group of cancers of the immune system. NHLs can occur at any age, and are often marked by enlarged lymph nodes, fever, and weight loss. There are many different types of NHL, and they can be divided into aggressive (fast-growing) and indolent (slow-growing) types, and are classified as either B-cell or T-cell NHL. B-cell NHLs include Burkitt's lymphoma, diffuse large B-cell lymphoma, follicular lymphoma, immunoblastic large cell lymphoma, precursor B-lymphoblastic lymphoma, and mantle cell lymphoma. T-cell NHLs include mycosis fungoides, anaplastic large cell lymphoma, and precursor T-lymphoblastic lymphoma. Lymphomas related to lymphoproliferative disorders following bone marrow or stem cell transplantation are usually B-cell NHLs. Prognosis and treatment depend on the stage and type of disease.

niacinamide
A vitamin being studied to increase the effect of radiation therapy on tumor cells. Also called nicotinamide.

Nicotiana tabacum
Tobacco. A plant with leaves that have high levels of the addictive chemical nicotine. The leaves may be smoked (in cigarettes, cigars, and pipes), applied to the gums (as dipping and chewing tobacco), or inhaled (as snuff). Tobacco leaves also contain many cancer-causing chemicals, and tobacco use and exposure to secondhand tobacco smoke have been linked to many types of cancer and other diseases.

nicotinamide
A vitamin being studied to increase the effect of radiation therapy on tumor cells. Also called niacinamide.

nicotine (NIH-kuh-TEEN)
An addictive, poisonous chemical found in tobacco. It can also be made in the laboratory. When it enters the body, nicotine causes an increased heart rate and use of oxygen by the heart, and a sense of well-being and relaxation. It is also used as an insecticide.

nicotine gum (NIH-kuh-TEEN...)
A chewing gum that contains a small dose of nicotine, which enters the blood by being absorbed through the lining of the mouth. This helps stop nicotine cravings and relieves symptoms that occur when a person is trying to quit smoking. A prescription is not needed for nicotine gum.

nicotine inhaler (NIH-kuh-TEEN in-HAY-ler)
A device used to inhale (breathe in) small doses of nicotine through the mouth. The nicotine is absorbed through the lining of the mouth and goes into the blood. This helps stop nicotine cravings, and relieves symptoms that occur when a person is trying to quit smoking. A prescription is needed for nicotine inhalers.

nicotine lozenge (NIH-kuh-TEEN LAH-zinj)
A hard candy-like tablet that contains a small dose of nicotine. The nicotine is absorbed through the lining of the mouth and goes into the blood. This helps stop nicotine cravings, and relieves symptoms that occur when a person is trying to quit smoking. A prescription is not needed for nicotine lozenges.

nicotine nasal spray (NIH-kuh-TEEN NAY-zul...)
A nose spray that contains a small dose of nicotine, which enters the blood by being absorbed through the lining of the nose. This helps stop nicotine cravings and relieves symptoms that occur when a person is trying to quit smoking. A prescription is needed for nicotine nasal spray.

nicotine patch (NIH-kuh-TEEN...)
A patch that sticks on the skin and contains a small dose of nicotine, which enters the blood by being absorbed through the skin. This helps stop nicotine cravings and relieves symptoms that occur when a person is trying to quit smoking. A prescription is not needed for nicotine patches.

nicotine replacement therapy (NIH-kuh-TEEN rih-PLAYS-munt THAYR-uh-pee)
A type of treatment that uses special products to give small, steady doses of nicotine to help stop cravings and relieve symptoms that occur when a person is trying to quit smoking. These products include nicotine gum, nicotine inhaler, nicotine nasal spray, nicotine lozenges, and nicotine patch. They do not contain any of the other chemicals found in tobacco products.

NIH
National Institutes of Health. NIH, the focal point of biomedical research in the United States, conducts research in its own laboratories; supports the research of non-Federal scientists in universities, medical schools, hospitals, and research institutions throughout the country and abroad; helps in the training of research investigators; and fosters communication of medical information. Access the NIH Web site at http://www.nih.gov.

nilutamide (nye-LOO-ta-mide)
A drug that blocks the effects of male hormones in the body. It belongs to the family of drugs called antiandrogens.

nimodipine
Belongs to a family of drugs called calcium channel blockers. It is being investigated for use with anticancer drugs to prevent or overcome drug resistance and improve response to chemotherapy.

nimustine (NY-mus-tine)
A substance that is being studied in the treatment of brain cancer. It belongs to the family of drugs called nitrosoureas.

nipple
In anatomy, the small raised area in the center of the breast through which milk can flow to the outside.

nipple discharge
Fluid coming from the nipple.

nitric acid
A toxic, corrosive, colorless liquid used to make fertilizers, dyes, explosives, and other chemicals.

nitrocamptothecin
An alkaloid drug belonging to a class of anticancer agents called topoisomerase inhibitors.

nitrosourea (nye-TRO-so-yoo-REE-ah)
An anticancer drug that can cross the blood-brain barrier. Carmustine and lomustine are nitrosoureas.

NK cell
Natural killer cell. A type of white blood cell that contains granules with enzymes that can kill tumor cells or microbial cells. Also called a large granular lymphocyte.

NMRI
Nuclear magnetic resonance imaging (NOO-klee-er mag-NET-ik REZ-o-nans IM-a-jing). A procedure in which radio waves and a powerful magnet linked to a computer are used to create detailed pictures of areas inside the body. These pictures can show the difference between normal and diseased tissue. NMRI makes better images of organs and soft tissue than other scanning techniques, such as CT or x-ray. NMRI is especially useful for imaging the brain, spine, the soft tissue of joints, and the inside of bones. Also called magnetic resonance imaging (MRI).

NMS
Neuroleptic malignant syndrome. A life-threatening condition that may be caused by certain drugs used to treat mental illness, nausea, or vomiting. Symptoms include high fever, sweating, unstable blood pressure, confusion, and stiffness.

node-negative
Cancer that has not spread to the lymph nodes.

node-positive
Cancer that has spread to the lymph nodes.

nodular parenchyma
A small mass of tissue within a gland or organ that carries out the specialized functions of the gland or organ.

nodule (NOD-yool)
A growth or lump that may be cancerous or noncancerous.

nolatrexed
A substance that is being studied in the treatment of liver cancer. It belongs to the family of drugs called thymidylate synthase inhibitors. Also called AG337 and Thymitaq.

nomogram (NAH-moh-GRAM)
A mathematical device or model that shows relationships between things. For example, a nomogram of height and weight measurements can be used to find the surface area of a person, without doing the math, to determine the right dose of chemotherapy. Nomograms of patient and disease characteristics can help predict the outcome of some kinds of cancer.

non-Hodgkin's lymphoma (non-HOJ-kinz lim-FOH-muh)
NHL. Any of a large group of cancers of the immune system. NHLs can occur at any age, and are often marked by enlarged lymph nodes, fever, and weight loss. There are many different types of NHL, and they can be divided into aggressive (fast-growing) and indolent (slow-growing) types, and are classified as either B-cell or T-cell NHL. B-cell NHLs include Burkitt's lymphoma, diffuse large B-cell lymphoma, follicular lymphoma, immunoblastic large cell lymphoma, precursor B-lymphoblastic lymphoma, and mantle cell lymphoma. T-cell NHLs include mycosis fungoides, anaplastic large cell lymphoma, and precursor T-lymphoblastic lymphoma. Lymphomas related to lymphoproliferative disorders following bone marrow or stem cell transplantation are usually B-cell NHLs. Prognosis and treatment depend on the stage and type of disease.

non-small cell lung cancer
A group of lung cancers that includes squamous cell carcinoma, adenocarcinoma, and large cell carcinoma.

nonblinded
Describes a clinical trial or other experiment in which the researchers know what treatments are being given to each study subject or experimental group. If human subjects are involved, they know what treatments they are receiving.

nonconsecutive case series
A clinical study that includes some, but not all, of the eligible patients identified by the researchers during the study registration period. This type of study does not usually have a control group.

noncontiguous lymphoma (non-kun-TIG-yoo-us lim-FOH-muh)
Lymphoma in which the lymph nodes containing cancer are not next to each other, but are on the same side of the diaphragm (the thin muscle below the lungs that helps breathing and separates the chest from the abdomen).

nonfunctioning tumor (non-FUNK-shuh-ning TOO-mer)
A tumor that is found in endocrine tissue but that does not make extra hormones (chemicals that travel in the blood and control the actions of other cells or organs).

nonhematologic cancer
Cancer that does not begin in the blood or bone marrow.

noni
Morinda citrifolia. A tropical shrub. An extract from the fruit is being studied as a treatment for cancer, and extracts from the fruit, leaves, or roots have been used in some cultures to treat other diseases.

noninvasive (NON-in-VAY-siv)
In medicine, it describes a procedure that does not require inserting an instrument through the skin or into a body opening. In cancer, it describes disease that has not spread outside the tissue in which it began.

nonlytic
In biology, refers to viruses that do not kill infected cells by disrupting their plasma membranes.

nonmalignant
Not cancerous.

nonmalignant hematologic disorder
A disorder of the blood. Some nonmalignant hematologic disorders may lead to leukemia.

nonmelanoma skin cancer
Skin cancer that arises in basal cells or squamous cells but not in melanocytes (pigment-producing cells of the skin).

nonmelanomatous
Having to do with skin cancer that develops in basal cells or squamous cells but not in melanocytes (pigment-producing cells of the skin).

nonmetastatic
Cancer that has not spread from the primary (original) site to other sites in the body.

nonopioid
A drug that is not an opioid. Examples include acetaminophen and nonsteroidal anti-inflammatory drugs (NSAIDS), such as aspirin and ibuprofen.

nonprescription
A medicine that can be bought without a prescription (doctor's order). Examples include analgesics (pain relievers) such as aspirin and acetaminophen. Also called over-the-counter (OTC).

nonrandomized clinical trial
A clinical trial in which the participants are not assigned by chance to different treatment groups. Participants may choose which group they want to be in, or they may be assigned to the groups by the researchers.

nonseminoma (non-sem-ih-NO-ma)
A group of testicular cancers that begin in the germ cells (cells that give rise to sperm). Nonseminomas are identified by the type of cell in which they begin and include embryonal carcinoma, teratoma, choriocarcinoma, and yolk sac carcinoma.

nonspecific immune cell
A cell (such as a phagocyte or a macrophage) that responds to many antigens, not just one antigen.

nonsteroidal anti-inflammatory drug
NSAID. A drug that decreases fever, swelling, pain, and redness.

nonsteroidal aromatase inhibitor
A drug that decreases the production of sex hormones (estrogen or testosterone) and slows the growth of tumors that need sex hormones to grow.

nontoxic
Not harmful or destructive.

noradrenaline (NOR-uh-dreh-nuh-lin)
A chemical made by some nerve cells and in the adrenal gland. It can act as both a neurotransmitter (a chemical messenger used by nerve cells) and a hormone (a chemical that travels in the blood and controls the actions of other cells or organs). Noradrenaline is released from the adrenal gland in response to stress and low blood pressure. Also called norepinephrine .

norepinephrine (NOR-ep-ih-NEF-rin)
A chemical made by some nerve cells and in the adrenal gland. It can act as both a neurotransmitter (a chemical messenger used by nerve cells) and a hormone (a chemical that travels in the blood and controls the actions of other cells or organs). Norepinephrine is released from the adrenal gland in response to stress and low blood pressure. Also called noradrenaline.

notary public (NOH-tuh-ree PUH-blik)
A person who has a license that gives them the legal power to witness the signing of documents, to certify that documents are real, and to take statements made under oath.

Novantrone
A drug used to treat advanced prostate cancer that does not respond to hormones, adult acute nonlymphocytic leukemia, and advanced or chronic multiple sclerosis. It is also being studied in the treatment of other cancers. It belongs to the family of drugs called antitumor antibiotics. Also called mitoxantrone.

novobiocin
An antibiotic drug used to treat infection.

NPO
A Latin abbreviation for "nothing by mouth."

NR-LU-10 antigen
A protein found on the surface of some cancers.

NSAID
Nonsteroidal anti-inflammatory drug. A drug that decreases fever, swelling, pain, and redness.

NSC 655649
A substance that is being studied in the treatment of cancer. It is similar to rebeccamycin. It belongs to the families of drugs called antineoplastic antibiotics and topoisomerase I inhibitors. Also called rebeccamycin analog.

nuclear grade
An evaluation of the size and shape of the nucleus in tumor cells and the percentage of tumor cells that are in the process of dividing or growing. Cancers with low nuclear grade grow and spread less quickly than cancers with high nuclear grade.

nuclear magnetic resonance imaging (NOO-klee-er mag-NET-ik REZ-o-nans IM-a-jing)
NMRI. A procedure in which radio waves and a powerful magnet linked to a computer are used to create detailed pictures of areas inside the body. These pictures can show the difference between normal and diseased tissue. NMRI makes better images of organs and soft tissue than other scanning techniques, such as CT or X-ray. NMRI is especially useful for imaging the brain, spine, the soft tissue of joints, and the inside of bones. Also called magnetic resonance imaging (MRI).

nuclear medicine scan
A method of diagnostic imaging that uses very small amounts of radioactive material. The patient is injected with a liquid that contains the radioactive substance, which collects in the part of the body to be imaged. Sophisticated instruments detect the radioactive substance in the body and process that information into an image.

nurse
A health professional trained to care for people who are ill or disabled.

nursing home
A place that gives care to people who have physical or mental disabilities and need help with activities of daily living (such as taking a bath, getting dressed, and going to the bathroom) but do not need to be in the hospital.

nutraceutical
A food or dietary supplement that is believed to provide health benefits.

nutrient
A chemical compound (such as protein, fat, carbohydrate, vitamins, or minerals) that make up foods. These compounds are used by the body to function and grow.

nutrition
The taking in and use of food and other nourishing material by the body. Nutrition is a 3-part process. First, food or drink is consumed. Second, the body breaks down the food or drink into nutrients. Third, the nutrients travel through the bloodstream to different parts of the body where they are used as "fuel" and for many other purposes. To give the body proper nutrition, a person has to eat and drink enough of the foods that contain key nutrients.

nutrition therapy (noo-TRIH-shun THAYR-uh-pee)
Treatment based on nutrition. It includes checking a person's nutrition status, and giving the right foods or nutrients to treat conditions such as those caused by diabetes, heart disease, and cancer. It may involve simple changes in a person's diet, or intravenous or tube feeding. Nutrition therapy may help patients recover more quickly and spend less time in the hospital. Also called medical nutrition therapy.

nutritional status (noo-TRIH-shuh-nul STA-tus)
The state of a person's health in terms of the nutrients in his or her diet.

nutritional supplement (noo-TRIH-shuh-nul SUH-pleh-ment)
A product that is added to the diet. A nutritional supplement is taken by mouth, and usually contains one or more dietary ingredients (including vitamins, minerals, herbs, amino acids, and enzymes). Also called dietary supplement.

nutritionist
A health professional with special training in nutrition who can help with dietary choices. Also called a dietitian.

nystatin
A drug that treats infections caused by fungi.

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O(6)-benzylguanine
A drug that may improve the response of cancer cells to chemotherapy.

oat cell cancer
An aggressive (fast-growing) cancer that usually forms in tissues of the lung and spreads to other parts of the body. The cancer cells look small and oval-shaped when looked at under a microscope. Also called small cell lung cancer.

obese
Having an abnormally high, unhealthy amount of body fat.

objective improvement
An improvement that can be measured by the health care provider (for example, when a tumor shrinks or there are fewer cancer cells in the blood).

objective response
A measurable response.

oblimersen
A substance that is being studied in the treatment of cancer. It may kill cancer cells by blocking the production of a protein that makes cancer cells live longer and by making them more sensitive to anticancer drugs. It belongs to the family of drugs called antisense oligodeoxyribonucleotides. Also called Genasense, augmerosen, and bcl-2 antisense oligodeoxynucleotide G3139.

observation
Closely monitoring a patient's condition but withholding treatment until symptoms appear or change. Also called watchful waiting.

observational study
A type of study in which individuals are observed or certain outcomes are measured. No attempt is made to affect the outcome (for example, no treatment is given).

obstruction
Blockage of a passageway.

obtundation (ob-tun-DAY-shun)
A dulled or reduced level of alertness or consciousness.

occult primary tumor (uh-KULT PRY-mayr-ee TOO-mer)
Cancer in which the site of the primary (original) tumor cannot be found. Most metastases from occult primary tumors are found in the head and neck.

occult stage non-small cell lung cancer
Cancer cells are found in sputum (mucus coughed up from the lungs), but no tumor can be found in the lung by imaging or bronchoscopy, or the primary tumor is too small to be assessed.

occupational therapist
A health professional trained to help people who are ill or disabled learn to manage their daily activities.

octreotide
A drug similar to the naturally occurring growth hormone inhibitor somatostatin. Octreotide is used to treat diarrhea and flushing associated with certain types of tumors.

octreotide scan
A type of radionuclide scan used to find carcinoid and other types of tumors. Radioactive octreotide, a drug similar to somatostatin, is injected into a vein and travels through the bloodstream. The radioactive octreotide attaches to tumor cells that have receptors for somatostatin. A radiation-measuring device detects the radioactive octreotide, and makes pictures showing where the tumor cells are in the body. This procedure is also called somatostatin receptor scintigraphy (SRS).

ocular melanoma
A rare cancer of melanocytes (cells that produce the pigment melanin) found in the eye. Also called intraocular melanoma.

odor (OH-der)
A smell.

odorant (OH-deh-runt)
A substance that gives off a smell.

off-label
Describes the legal use of a prescription drug to treat a disease or condition for which the drug has not been approved by the US Food and Drug Administration.

ofloxacin
An antibiotic drug used to treat infection. It belongs to the family of drugs called quinolone antibiotics.

OGF
Opioid growth factor. A substance made by the body and in the laboratory. It is being studied in the treatment of cancer. It belongs to the families of drugs called angiogenesis inhibitors and biological response modifiers.

OGX-011
A substance that is being studied as a treatment for cancer. It belongs to the family of drugs called antisense oligonucleotides.

ointment (OYNT-munt)
A substance used on the skin to soothe or heal wounds, burns, rashes, scrapes, or other skin problems. Also called unguent.

olfaction (ol-FAK-shun)
The sense of smell.

olfactory (ol-FAK-tuh-ree)
Having to do with the sense of smell.

olfactory system (ol-FAK-tuh-ree SIS-tem)
The parts of the body involved in sensing smell, including the nose and many parts of the brain. Smell may affect emotion, behavior, memory, and thought.

olfactory transduction (ol-FAK-tuh-ree tranz-DUK-shun)
A series of events in which cells in the nose bind to scent-bearing molecules and send electrical signals to the brain where they are perceived as smells.

oligoastrocytoma
A rare type of brain tumor made up of two kinds of cells, oligodendrocytes and astrocytes, which are brain cells that nourish and support nerve cells. Also called mixed glioma.

oligodendroglial tumor
A rare, slow-growing tumor that begins in the oligodendrocytes (brain cells that nourish and support nerve cells). Also called an oligodendroglioma.

oligodendroglioma (OL-ih-go-den-dro-glee-O-ma)
A rare, slow-growing tumor that begins in the oligodendrocytes (brain cells that nourish and support nerve cells). Also called an oligodendroglial tumor.

oltipraz
A drug used in cancer prevention.

omega-3 fatty acid
A type of fat obtained in the diet and involved in immunity.

omentectomy
Surgery to remove part or all of the omentum.

omentum (oh-MEN-tum)
A fold of the peritoneum (the thin tissue that lines the abdomen) that surrounds the stomach and other organs in the abdomen.

omeprazole
A drug that inhibits gastric acid secretion.

Ommaya reservoir (o-MY-a REZ-er-vwahr)
A device surgically placed under the scalp and used to deliver anticancer drugs to the fluid surrounding the brain and spinal cord.

oncogene
A gene that normally directs cell growth. If altered, an oncogene can promote or allow the uncontrolled growth of cancer. Alterations can be inherited or caused by an environmental exposure to carcinogens.

oncologist (on-KOL-o-jist)
A doctor who specializes in treating cancer. Some oncologists specialize in a particular type of cancer treatment. For example, a radiation oncologist specializes in treating cancer with radiation.

oncology
The study of cancer.

oncology nurse
A nurse who specializes in treating and caring for people who have cancer.

oncology pharmacy specialist
A person who works with an oncologist to prepare anticancer drugs.

oncolysate
An extract made from cancer cells that are infected with a lytic strain of virus. The extract contains both cancer cell proteins and virus proteins. Oncolysates are being studied as cancer vaccines.

oncolysis
The breakdown, or lysis, of a tumor. This can occur by mechanical means, chemicals, or infectious agents such as viruses. Oncolytic viruses do not lyse most normal cells.

oncolytic virotherapy (on-koh-LIT-ik VY-roh-THAYR-uh-pee)
Treatment using a virus which has been changed in the laboratory to find and destroy cancer cells without harming healthy cells. It is a type of targeted therapy. Also called virotherapy.

Onconase
A substance that is being studied in the treatment of cancer. It belongs to the family of drugs called ribonuclease enzymes. Also called ranpirnase.

ondansetron
A drug that prevents or reduces nausea and vomiting. It belongs to the family of drugs called antiemetics.

onset of action
The length of time it takes for a medicine to start to work.

ONYX-015
A modified cold virus that selectively grows in and destroys certain types of cancer cells and leaves normal cells undamaged.

oophorectomy (o-o-for-EK-toe-mee)
Surgery to remove one or both ovaries.

open biopsy
A procedure in which a surgical incision (cut) is made through the skin to expose and remove tissues. The biopsy tissue is examined under a microscope by a pathologist. An open biopsy may be done in the doctor's office or in the hospital, and may use local anesthesia or general anesthesia. A lumpectomy to remove a breast tumor is a type of open biopsy.

open colectomy (ko-LEK-toe-mee)
An operation to remove all or part of the colon through a long incision made in the wall of the abdomen. When only part of the colon is removed, it is called a partial colectomy.

open label study
A type of study in which both the health providers and the patients are aware of the drug or treatment being given.

operable
Describes a condition that can be treated by surgery.

ophthalmic
Having to do with the eye.

ophthalmoscope (off-THAL-mo-skope)
A lighted instrument used to examine the inside of the eye, including the retina and the optic nerve.

opiate
A drug used to treat pain. It contains opium or a substance made from opium (such as morphine).

opioid
A drug used to treat moderate to severe pain. Opioids are similar to opiates such as morphine and codeine, but they do not contain and are not made from opium.

opioid growth factor (OH-pee-OYD grohth FAK-ter)
OGF. A substance made by the body and in the laboratory. It is being studied in the treatment of cancer. It belongs to the families of drugs called angiogenesis inhibitors and biological response modifiers.

opportunistic infection
An infection caused by an organism that does not normally cause disease. Opportunistic infections occur in people with weakened immune systems.

optic nerve
The nerve that carries messages from the retina to the brain.

oral
By or having to do with the mouth.

oral and maxillofacial surgeon
A dentist who specializes in surgery of the mouth, face, and jaw.

oral cancer (OR-ul KAN-ser)
Cancer that forms in tissues of the lip or mouth. This includes the front two thirds of the tongue, the upper and lower gums, the lining inside the cheeks and lips, the bottom of the mouth under the tongue, the bony top of the mouth, and the small area behind the wisdom teeth.

oral cavity
The mouth.

oral contraceptive pill (OR-ul KON-truh-SEP-tiv)
A pill used to prevent pregnancy. It contains hormones that block the release of eggs from the ovaries. Most oral contraceptives include estrogen and progestin. Also called birth control pill.

oral surgeon
A dentist with special training in surgery of the mouth and jaw.

orchidectomy
Surgery to remove one or both testicles. Also called orchiectomy.

orchiectomy (or-kee-EK-toe-mee)
Surgery to remove one or both testicles. Also called orchidectomy.

organ
A part of the body that performs a specific function. For example, the heart is an organ.

organism
A living thing, such as an animal, a plant, a bacterium, or a fungus.

Oriental medicine (OR-ee-EN-tul MEH-dih-sin)
A medical system that has been used for thousands of years to prevent, diagnose, and treat disease. It is based on the belief that qi (the body's vital energy) flows along 20 meridians (channels) throughout the body and keeps a person's spiritual, emotional, mental, and physical health in balance. Oriental medicine aims to restore the body's balance and harmony between the natural opposing forces of yin and yang, which can block qi and cause disease. Oriental medicine includes acupuncture, diet, herbal therapy, meditation, physical exercise, and massage. Also called traditional Chinese medicine.

oropharyngeal cancer (or-oh-fuh-RIN-jee-ul KAN-ser)
Cancer that forms in tissues of the oropharynx (the part of the throat at the back of the mouth, including the soft palate, the base of the tongue, and the tonsils). Most oropharyngeal cancers are squamous cell carcinomas (cancer that begins in flat cells lining the oropharynx).

oropharynx (or-o-FAIR-inks)
The part of the throat at the back of the mouth. It includes the soft palate, the base of the tongue, and the tonsils.

orthodox medicine
A system in which medical doctors and other healthcare professionals (such as nurses, pharmacists, and therapists) treat symptoms and diseases using drugs, radiation, or surgery. Also called conventional medicine, Western medicine, mainstream medicine, biomedicine, and allopathic medicine.

OSI-7904L
A substance that is being studied in the treatment of cancer. It belongs to the family of drugs called thymidylate synthase inhibitors.

osmolality
The concentration of particles dissolved in a fluid. The osmolality of serum can help diagnose several medical conditions such as dehydration, diabetes, and shock.

osmotic (oz-MAH-tik)
Having to do with osmosis (the passage of a liquid through a membrane from a less concentrated solution to a more concentrated one). This causes the more concentrated solution to become diluted, and makes the concentrations in both solutions more equal. Osmotic also refers to a type of laxative that increases the amount of water in the large intestine, which softens the stool to help it pass more easily.

osteitis deformans
A chronic condition in which both the breakdown and regrowth of bone are increased. Osteitis deformans occurs most frequently in the pelvic and leg bones, skull, and lower spine. It is most common in older individuals, and may lead to bone pain, deformities, and fractures. Also called Paget's disease of bone.

osteogenic sarcoma
A cancer of the bone that usually affects the large bones of the arm or leg. It occurs most commonly in young people and affects more males than females. Also called osteosarcoma.

osteolytic
Causing the breakdown of bone.

osteoporosis (OSS-tee-oh-pa-ROW-sis)
A condition that is characterized by a decrease in bone mass and density, causing bones to become fragile.

osteosarcoma (AHS-tee-o-sar-KO-ma)
A cancer of the bone that usually affects the large bones of the arm or leg. It occurs most commonly in young people and affects more males than females. Also called osteogenic sarcoma.

ostomy (AHS-toe-mee)
An operation to create an opening (a stoma) from an area inside the body to the outside. Colostomy and urostomy are types of ostomies.

OTC
Over-the-counter. A medicine that can be bought without a prescription (doctor's order). Examples include analgesics (pain relievers) such as aspirin and acetaminophen. Also called nonprescription.

OTI-010
A preparation of laboratory-treated human mesenchymal stem cells that is being studied for its ability to prevent or decrease graft-versus-host disease in patients having stem cell transplants.

otolaryngologist (OAT-oh-LAR-in-GOL-uh-jist)
A doctor who specializes in treating diseases of the ear, nose, and throat. Also called an ENT (ear, nose, and throat) doctor.

ounce
A measure of weight (one-sixteenth pound) and volume (one-eighth cup).

outcome
A specific result or effect that can be measured. Examples of outcomes include decreased pain, reduced tumor size, and improvement of disease.

outpatient
A patient who visits a health care facility for diagnosis or treatment without spending the night. Sometimes called a day patient.

ovarian
Having to do with the ovaries, the female reproductive glands in which the ova (eggs) are formed. The ovaries are located in the pelvis, one on each side of the uterus.

ovarian ablation
Surgery, radiation therapy, or a drug treatment to stop the functioning of the ovaries. Also called ovarian suppression.

ovarian cancer (oh-VAYR-ee-un KAN-ser)
Cancer that forms in tissues of the ovary. Most ovarian cancers are either ovarian epithelial carcinomas (cancer that begins in cells that line the ovary) or malignant germ cell tumors (cancer that begins in egg cells).

ovarian epithelial cancer
Cancer that occurs in the cells lining the ovaries.

ovarian germ cell tumor (oh-VAYR-ee-un jerm sel TOO-mer)
An abnormal mass of tissue that forms in germ (egg) cells in the ovary (female reproductive gland in which the eggs are formed). These tumors usually occur in teenage girls or young women, usually affect just one ovary, and can be benign (not cancer) or malignant (cancer). The most common ovarian germ cell tumor is called dysgerminoma.

ovarian suppression
Surgery, radiation therapy, or a drug treatment to stop the functioning of the ovaries. Also called ovarian ablation.

ovary (O-va-ree)
One of a pair of female reproductive glands in which the ova, or eggs, are formed. The ovaries are located in the pelvis, one on each side of the uterus.

over-the-counter
OTC. A medicine that can be bought without a prescription (doctor's order). Examples include analgesics (pain relievers) such as aspirin and acetaminophen. Also called nonprescription.

overactive thyroid
Too much thyroid hormone. Symptoms include weight loss, chest pain, cramps, diarrhea, and nervousness. Also called hyperthyroidsm.

overall survival
The percentage of subjects in a study who have survived for a defined period of time. Usually reported as time since diagnosis or treatment. Also called the survival rate.

overdose (OH-ver-DOHS)
An amount of drug that is more than what should be taken at one time.

overexpress
An excess of a particular protein on the surface of a cell.

overgrowth syndrome
A group of genetic disorders in which there is an abnormal increase in the size of the body or a body part that is often noted at birth. Examples of overgrowth syndromes include neurofibromatosis, Sotos syndrome, Beckwith-Wiedemann syndrome, Simpson-Golabi-Behmel syndrome, Weaver syndrome, Proteus syndrome, Sturge-Weber syndrome, and fragile X syndrome. Many of these syndromes increase the risk of cancer.

overweight
Being too heavy for one's height. Excess body weight can come from fat, muscle, bone, and/or water retention. Being overweight does not always mean being obese.

ovulation (ov-yoo-LA-shun)
The release of an egg from an ovary during the menstrual cycle.

oxaliplatin
A drug that is used to treat colorectal cancer, and is being studied in the treatment of other types of cancer. It belongs to the family of drugs called platinum compounds. Also called Eloxatin.

oxandrolone (ox-AN-dro-lone)
A drug used to help patients gain weight after injury, chronic infection, or severe illness. It belongs to the family of drugs called anabolic steroids.

OXi-104
An anticancer drug being evaluated in combination with cisplatin.

oxidation
Process in which molecules are split to give products that have unpaired electrons.

oxidative metabolism
A chemical process in which oxygen is used to make energy from carbohydrates (sugars). Also known as aerobic respiration, cell respiration, or aerobic metabolism.

oxidative stress
A condition in which antioxidant levels are lower than normal. Antioxidant levels are usually measured in blood plasma.

oxide (OK-side)
A type of chemical substance that is a combination of oxygen and another substance. Oxides are found in essential oils.




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