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L-3,5,5’-tetraiodothyronine  (...TEH-truh-i-oh-doh-THY-roh-neen)
A hormone that is made by the thyroid gland and contains iodine. L-3,5,5’-tetraiodothyronine increases the rate of chemical reactions in cells and helps control growth and development. L-3,5,5’-tetraiodothyronine can also be made in the laboratory and is used to treat thyroid disorders. Also called thyroxine, T4, and thyroxin.

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-arginine  (… AR-jih-neen)
One of the twenty common amino acids (building blocks of proteins). L-arginine is being studied as a nutritional supplement in the treatment and prevention of cancer and other conditions. Also called arginine.

L-asparaginase  (... as-PA-ruh-jih-nayz)
A drug that is used to treat acute lymphoblastic leukemia (ALL) and is being studied in the treatment of some other types of cancer. It is an enzyme taken from the bacterium Escherichia coli (E. coli). It breaks down the amino acid asparagine and may block the growth of tumor cells that need asparagine to grow. Also called asparaginase and Elspar.

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.

L-glutamic acid  (... gloo-TA-mik A-sid)
One of twenty amino acids (molecules that join together to form proteins). L-glutamic acid may help nerve cells send and receive information from other cells. It is being studied for its ability to decrease or prevent nerve damage caused by anticancer drugs. Also called glutamic acid.

L-norgestrel  (... nor-JES-trel)
A form of the hormone progesterone that is made in the laboratory and used to prevent pregnancy. It is being studied in the prevention of ovarian and endometrial cancer, and in the treatment of other conditions. L-norgestrel is a type of oral contraceptive. Also called levonorgestrel and Plan B.

L-threo-dihydrosphingosine  (...THREE-oh-dy-HY-drose-FIN-guh-seen)
A substance that is being studied in the treatment of cancer. It belongs to the family of drugs called protein kinase inhibitors. Also called safingol.

lab-on-a-chip  
An instrument that uses very small amounts of fluid on a microchip to do certain laboratory tests. A lab-on-a-chip may use body fluids or solutions containing cells or cell parts to diagnose diseases. Also called microfluidic device.

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.

lactase  (LAK-tayz)
An enzyme that breaks down lactose, a type of sugar found in milk and milk products.

lactate dehydrogenase  (LAK-tayt dee-hy-DRAH-jeh-nayz)
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 lactate dehydrogenase in the blood may be a sign of tissue damage and some types of cancer or other diseases. Also called lactic acid dehydrogenase and LDH.

lactic acid  (LAK-tik A-sid)
A substance made from sugars in milk, by the action of certain enzymes. It is used in skin care products to reduce wrinkles and soften the skin. It is also being studied in the treatment of hand-foot syndrome (a condition marked by pain, swelling, numbness, tingling, or redness of the hands or feet) in patients receiving chemotherapy. Lactic acid is also made in muscles in the body and is used in many chemical processes in the body. It is a type of alpha hydroxyl acid.

lactic acid dehydrogenase  (LAK-tik A-sid dee-hy-DRAH-jeh-nayz)
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 and LDH.

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.

Langerhans cell histiocytosis  (LANG-er-HANZ sel HIS-tee-oh-sy-TOH-sis)
A group of rare disorders in which too many Langerhans cells (a type of white blood cell) grow in certain tissues and organs including the bones, skin, and lungs, and damage them. Langerhans cell histiocytosis may also affect the pituitary gland (which makes hormones that control other glands and many body functions, especially growth). Langerhans cell histiocytosis is most common in children and young adults. Also called LCH.

lanolin  (LA-noh-lin)
An oily substance taken from sheep's wool. Lanolin is used in moisturizing creams and lotions to treat dry, itchy skin.

Lanoxin  (luh-NOK-sin)
A drug used to treat irregular heartbeat and some types of heart failure. It is also being studied in the treatment of some types of cancer. Lanoxin helps the heart work normally by controlling the amount of calcium that goes into the heart muscle. It also may kill cancer cells and make them more sensitive to anticancer drugs. It is a type of cardiac glycoside. Also called digoxin.

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 PROS-tuh-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-ROS-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  (LA-puh-RAH-toh-mee)
A surgical incision made in the wall of the abdomen.

lapatinib  (luh-PA-tih-nib)
A drug used with another anticancer drug to treat breast cancer that is HER2 positive and has advanced or metastasized (spread to other parts of the body) after treatment with other drugs. Lapatinib is also being studied in the treatment of other types of cancer. It is a type of ErbB-2 and EGFR dual tyrosine kinase inhibitor. Also called lapatinib ditosylate, GW572016, and Tykerb.

lapatinib ditosylate  (luh-PA-tih-nib dy-TOH-sih-layt)
A drug used with another anticancer drug to treat breast cancer that is HER2 positive and has advanced or metastasized (spread to other parts of the body) after treatment with other drugs. Lapatinib ditosylate is also being studied in the treatment of other types of cancer. It is a type of ErbB-2 and EGFR dual tyrosine kinase inhibitor. Also called lapatinib, GW572016, and Tykerb.

lappa  
A plant whose seeds and root have been used in some cultures to treat certain medical problems. It may have antioxidant effects. The scientific name is Arctium lappa. 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 natural killer cell and NK 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  (LA-rin-JEK-toh-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  (LAYR-inks)
The area of the throat containing the vocal cords and used for breathing, swallowing, and talking. Also called 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  (LAY-zer THAYR-uh-pee)
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.

late-stage cancer  
A term used to describe cancer that is far along in its growth, and has spread to the lymph nodes or other places in the body.

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. The scientific name is Lavandula angustifolia. Also called English lavender and true lavender.

laxative  
A substance that promotes bowel movements.

LCH  
A group of rare disorders in which too many Langerhans cells (a type of white blood cell) grow in certain tissues and organs including the bones, skin, and lungs, and damage them. LCH may also affect the pituitary gland (which makes hormones that control other glands and many body functions, especially growth). LCH is most common in children and young adults. Also called Langerhans cell histiocytosis.

LCIS  
Lobular carcinoma in situ. A condition in which abnormal cells are found in the lobules of the breast. LCIS seldom becomes invasive cancer; however, having it in one breast increases the risk of developing breast cancer in either breast. Also called lobular carcinoma in situ.

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 and lactate 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  (...THAYR-uh-pee)
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. Also called light-emitting diode therapy.

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 and loop electrosurgical excision procedure.

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  (LY-oh-my-OH-muh)
A benign smooth muscle tumor, usually in the uterus or gastrointestinal tract. Also called fibroid.

leiomyosarcoma  (LY-oh-MY-oh-sar-KOH-muh)
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.

lemon  
A small, yellow citrus fruit that is a source of citric acid and ascorbic acid (vitamin C). The juice is used to flavor food and drink and to prevent scurvy. Lemon oil (scented liquid taken from the peel) is used in aromatherapy. The scientific name of the lemon tree is Citrus limon.

lenalidomide  (leh-nah-LID-oh-mide)
A drug that is similar to thalidomide, and is used to treat multiple myeloma and certain types of anemia. It is also being studied in the treatment of other types of cancer. Lenalidomide belongs to the family of drugs called angiogenesis inhibitors. Also called CC-5013 and Revlimid.

lens  (lenz)
A clear disk that focuses light, as in a camera or microscope. In the eye, the lens is a clear, curved structure at the front of the eye behind the pupil. It focuses light rays that enter the eye through the pupil, making an image on the retina (light-sensitive layers of nerve tissue at the back of the eye).

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 is contained in very tiny, fat-like particles. It may have fewer side effects and work better than paclitaxel. It is being studied in the treatment of several types of cancer. LEP-ETU blocks the ability of cells to divide and may kill cancer cells. It is a type of mitotic inhibitor and a type of antimicrotubule agent. Also called paclitaxel liposome and PNU-93914.

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

leptomeningeal  (LEP-toh-meh-NIN-jee-ul)
Having to do with the two innermost meninges (thin layers of tissue that cover and protect the brain and spinal cord).

leptomeningeal cancer  (LEP-toh-meh-NIN-jee-ul KAN-ser)
A tumor that involves the two innermost meninges (thin layers of tissue that cover and protect the brain and spinal cord).

leptomeningeal metastasis  (LEP-toh-meh-NIN-jee-ul meh-TAS-tuh-sis)
Cancer that has spread from the original (primary) tumor to the two innermost meninges (thin layers of tissue that cover and protect the brain and spinal cord).

leridistim  
A substance being studied for its ability to stimulate the production of blood cells during chemotherapy. It is a type of colony-stimulating factor. Also called 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).

lestaurtinib  (leh-STOR-tih-nib)
A drug being studied in the treatment of acute leukemias and some other types of cancer. It binds to a protein that is present on the surface of some types of cancer cells and stops them from dividing. Lestaurtinib is a type of receptor tyrosine kinase inhibitor and a type of indolocarbazole alkaloid. Also called CEP-701.

lethargy  (LEH-thur-jee)
A condition marked by drowsiness and an unusual lack of energy and mental alertness. It can be caused by many things, including illness, injury, or drugs.

letrozole  (LET-ruh-zole)
A drug used to treat advanced breast cancer in postmenopausal women. Letrozole causes a decrease in the amount of estrogen made by the body. It is a type of aromatase inhibitor. Also called Femara.

leucovorin  (LOO-koh-VOR-in)
The active ingredient in a drug used to reduce the toxic effects of folic acid antagonists (substances that block the action of folic acid), especially the anticancer drug methotrexate. It is also used to treat anemia and it is used with fluorouracil to treat symptoms of advanced colorectal cancer. It is also being studied in the treatment of other types of cancer and other conditions. Leucovorin is a form of folic acid, a B-complex vitamin that the body needs to make red blood cells and to function and stay healthy. Leucovorin is a type of chemoprotective agent and a type of chemosensitizing agent. Also called folinic acid and Citrovorum factor.

leucovorin calcium  (LOO-koh-VOR-in KAL-see-um)
A drug used to reduce the toxic effects of folic acid antagonists (substances that block the action of folic acid), especially the anticancer drug methotrexate. It is also used to treat anemia and it is used with fluorouracil to treat symptoms of advanced colorectal cancer. It is also being studied in the treatment of other types of cancer and other conditions. Leucovorin calcium is a form of folic acid, a B-complex vitamin that the body needs to make red blood cells and to function and stay healthy. Leucovorin calcium is a type of chemoprotective agent and a type of chemosensitizing agent. Also called calcium levoleucovorin and Wellcovorin.

leukapheresis  (LOO-kuh-feh-REE-sis)
Removal of the blood to collect specific blood cells. The remaining blood is returned to the body.

leukemia  (loo-KEE-mee-uh)
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-koh-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-koh-PEE-nee-uh)
A condition in which the number of leukocytes (white blood cells) in the blood is reduced.

leukoplakia  (LOO-koh-PLAY-kee-uh)
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)
The active ingredient in a drug used to treat symptoms of advanced prostate cancer. It is also used to treat early puberty in children and certain gynecologic conditions. It is being studied in the treatment of other conditions and types of cancer. Leuprolide blocks the body from making testosterone (a male hormone) and estradiol (a female hormone). It may stop the growth of prostate cancer cells that need testosterone to grow. It is a type of gonadotropin-releasing hormone analog.

leuprolide acetate  (LOO-proh-lide A-seh-tayt)
A drug used to treat symptoms of advanced prostate cancer. It is also being studied in the treatment of other conditions and types of cancer. The active ingredient leuprolide blocks the body from making testosterone (a male hormone) and estradiol (a female hormone). It may stop the growth of prostate cancer cells that need testosterone to grow. Some brands of leuprolide are also used to treat early puberty in children and certain gynecologic conditions. Leuprolide acetate is a type of gonadotropin-releasing hormone analog. Also called Eligard, Lupron, and Viadur.

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.

levetiracetam  (lee-vih-ty-RAS-ih-tam)
A drug used to treat seizures (involuntary muscle movements) caused by epilepsy (a group of brain disorders). Levetiracetam is being studied in the treatment of seizures in patients with cancer that has spread to the brain. It is a type of anticonvulsant. Also called Keppra.

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.

levonorgestrel  (LEE-voh-nor-JES-trel)
A form of the hormone progesterone that is made in the laboratory and used to prevent pregnancy. It is being studied in the prevention of ovarian and endometrial cancer, and in the treatment of other conditions. Levonorgestrel is a type of oral contraceptive. Also called L-norgestrel and Plan B.

Levulan  (LEH-vyoo-lan)
A drug used to treat actinic keratosis (a skin condition that may become cancer). The drug is also being studied in the treatment of squamous cell and basal cell skin cancers and other types of cancer. When Levulan is taken up by cells, including cancer cells, and then exposed to certain types of light, it becomes active and kills the cells. It is a type of photosensitizing agent. Also called aminolevulinic acid hydrochloride and Levulan Kerastick.

Levulan Kerastick  (LEH-vyoo-lan KER-uh-stik)
A drug used to treat actinic keratosis (a skin condition that may become cancer). The drug is also being studied in the treatment of squamous cell and basal cell skin cancers and other types of cancer. When Levulan Kerastick is taken up by cells, including cancer cells, and then exposed to certain types of light, it becomes active and kills the cells. It is a type of photosensitizing agent. Also called aminolevulinic acid hydrochloride and Levulan.

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.

lexatumumab  (lek-suh-TOO-moo-mab)
A monoclonal antibody being studied in the treatment of some types of cancer. Monoclonal antibodies are made in the laboratory and can locate and bind to substances in the body, including cancer cells. Lexatumumab binds to a protein on the surface of tumor cells, which causes them to die.

LGD1069  
A drug used to treat skin problems caused by cutaneous T-cell lymphoma that have not gotten better after other treatment. It is also being studied in the treatment of other types of cancer. LGD1069 is a type of retinoid. Also called bexarotene and Targretin.

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

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. Also called luteinizing hormone-releasing hormone agonist.

Lhermitte's sign  (layr-MEETZ ...)
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.

licorice root extract  (LIH-kuh-rish … EK-strakt)
A substance prepared from dried roots of the plant Glycyrrhiza glabra. It is used as a flavoring in medicines, drinks, and sweets, and it is being studied in the treatment of cancer. Licorice root extract contains several compounds that reduce inflammation, kill certain bacteria and viruses, act like estrogen and other hormones, and may cause cancer cells to die. It is a type of antioxidant.

lidocaine  (LY-duh-kane)
A substance used to relieve pain by blocking signals at the nerve endings in skin. It can also be given intravenously to stop heart arrhythmias. It is a type of local anesthetic and antiarrhythmic.

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 therapy  (… THAYR-uh-pee)
The treatment of disease with certain types of light. Light therapy can use lasers, LED, fluorescent lamps, and ultraviolet or infrared radiation. Also called phototherapy.

light-emitting diode therapy  (lite-ee-MIT-ing THAYR-uh-pee)
Treatment with drugs that become active and may kill cancer cells when exposed to light. Light-emitting diode therapy is type of photodynamic therapy which uses a special type of light to activate the drug. Also called LED therapy.

lignan  (LIG-nun)
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  (LIM per-FYOO-zhun)
A procedure 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 (a tight band around the limb), 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, MeV linear accelerator, and 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, MeV linear accelerator, and 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.

Lioresal  (lih-OR-eh-sal)
A drug that is used to treat certain types of muscle spasms and is being studied in the treatment of liver cancer. Lioresal relaxes muscles by blocking certain nerve receptors in the spinal cord. It is a type of antispasmodic. Also called baclofen and Kemstro.

liothyronine sodium  (LY-oh-THY-roh-neen SOH-dee-um)
A drug that is used to treat certain thyroid (a gland located near the voice box) conditions. It is also being studied in the treatment of thyroid cancer. Liothyronine sodium is made in the laboratory and is a form of the thyroid hormone triiodthyronine (T3). Also called Cytomel and Triostat.

lipid  
Fat.

Lipitor  (LIH-pih-tor)
A drug used to treat high cholesterol. It is also being studied in the prevention of colon cancer and in the treatment of some types of cancer and other conditions. Lipitor is a type of HMG-CoA reductase inhibitor (statin). Also called atorvastatin calcium and atorvastatin.

LipoDox  
A form of the anticancer drug doxorubicin that is contained in very tiny, fat-like particles. It may have fewer side effects and work better than doxorubicin. LipoDox is used to treat ovarian cancer, AIDS-related Kaposi sarcoma, and multiple myeloma in patients whose disease has not gotten better after treatment with other anticancer drugs. It may be used together with other anticancer drugs. It is also being studied in the treatment of other types of cancer. LipoDox is a type of anthracycline antitumor antibiotic. Also called doxorubicin hydrochloride liposome, Doxil, Evacet, and Dox-SL.

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  (LY-poh-SOH-mul)
A drug preparation that contains the active drug inside very tiny, fat-like particles. This form is easier for the body to absorb and allows more drug to get to the target area of the body, such as a tumor. Liposomal drugs may have fewer side effects and work better than other forms of the drug.

liposomal cytarabine  (LY-poh-SOH-mul sy-TAYR-uh-been)
A form of the anticancer drug cytarabine that is contained inside very tiny, fat-like particles. It may have fewer side effects and work better than cytarabine. It is used to treat lymphoma that has spread to the meninges (three thin layers of tissue that cover and protect the brain and spinal cord). It is also being studied in the treatment of other types of cancer. It is a type of antimetabolite. Also called cytarabine liposome and Depo-Cyt.

liposomal SN-38  (LY-poh-SOH-mul…)
A form of the anticancer drug irinotecan that is contained in very tiny, fat-like particles. It may have fewer side effects and work better than irinotecan alone. Liposomal SN-38 is being studied in the treatment of advanced colorectal cancer and other types of cancer. Liposomal SN-38 blocks the ability of cells to divide and grow. It may stop the growth of tumor cells. It is a type of topoisomerase inhibitor and a type of irinotecan (CPT-11) derivative. Also called SN-38 liposome.

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.

lithium  (LIH-thee-um)
A soft metal. Lithium salts are used to treat certain mental disorders, especially bipolar (manic depressive) disorder. Lithium salts include lithium carbonate and lithium citrate.

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

liver cancer  
Primary liver cancer is cancer that forms in the tissues of the liver. Secondary liver cancer is cancer that spreads to the liver from another part of the body.

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 metastasis  (...meh-TAS-tuh-sis)
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  (... IH-myoo-noh-TOK-sin)
A toxic substance linked to an antibody that attaches to tumor cells and kills them.

LMB-2 immunotoxin  (... IH-myoo-noh-TOK-sin)
A toxic substance linked to an antibody that attaches to tumor cells and kills them.

LMB-7 immunotoxin  (... IH-myoo-noh-TOK-sin)
A toxic substance linked to an antibody that attaches to tumor cells and kills them.

LMB-9 immunotoxin  (... IH-myoo-noh-TOK-sin)
A toxic substance linked to an antibody that attaches to tumor cells and kills them.

lobaplatin  (LOH-buh-PLA-tin)
A substance that contains the metal platinum and may kill cancer cells by damaging their DNA and stopping them from dividing. It is a type of alkylating agent.

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

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

lobeline  (LOH-beh-leen)
A substance that comes from a plant known as Indian tobacco, which is different from the tobacco used to make smoking products. It has been studied as a way to help people stop smoking. It is a type of alkaloid.

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  (LAH-byuh-ler KAR-sih-NOH-muh)
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  (LAH-byuh-ler KAR-sih-NOH-muh in SY-too)
LCIS. A condition in which abnormal cells are found in the lobules of the breast. Lobular carcinoma in situ seldom becomes invasive cancer; however, having it in one breast increases the risk of developing breast cancer in either breast. Also called LCIS.

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

local anesthesia  (... A-nes-THEE-zhuh)
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  (...THAYR-uh-pee)
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  (...muh-LIG-nunt meh-zuh-thee-lee-OH-muh)
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  (... ad-VANST KAN-ser)
Cancer that has spread from where it started to nearby tissue or lymph nodes.

locally recurrent cancer  (... ree-KER-ent KAN-ser)
Cancer that has recurred (come back) at or near the same place as the original (primary) tumor, usually after a period of time during which the cancer could not be detected.

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.

Lofibra  (loh-FY-bruh)
A drug used to treat high levels of cholesterol and triglycerides in the blood. Lofibra is being studied in the treatment of advanced cancers in young patients and in the treatment of other conditions. It is a type of antilipidemic agent. Also called fenofibrate and TriCor.

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

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

loperamide hydrochloride  (loh-PER-uh-mide HY-droh-KLOR-ide)
A drug used to treat diarrhea. Loperamide hydrochloride slows the movement of the muscles in the small intestine to allow more water to be taken out of the feces (waste matter) and more nutrients to be absorbed. Also called Imodium.

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.

losartan  (loh-SAR-tan)
A drug used to treat high blood pressure. Losartan blocks the action of chemicals that make blood vessels constrict (get narrower). It is a type of angiotensin II receptor antagonist. Also called losartan potassium and Cozaar.

losartan potassium  (loh-SAR-tan puh-TA-see-um)
A drug used to treat high blood pressure. Losartan potassium blocks the action of chemicals that make blood vessels constrict (get narrower). It is a type of angiotensin II receptor antagonist. Also called losartan and Cozaar.

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

lovastatin  (LOH-vuh-STA-tin)
A drug used to lower the amount of cholesterol in the blood. It is also being studied in the prevention and treatment of some types of cancer. Lovastatin is a type of HMG-CoA reductase inhibitor (statin). Also called Mevacor.

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  (... lim-FOH-muh)
A type of lymphoma that tends to grow and spread slowly, and has few symptoms. Also called indolent lymphoma.

low-grade squamous intraepithelial lesion  (... SKWAY-mus IN-truh-eh-pih-THEE-lee-ul LEE-zhun)
A condition in which the cells of the uterine cervix are slightly abnormal. Low-grade squamous intraepithelial lesion is not cancer. Also called LSIL.

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

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

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  (LUM-bar PUNK-cher)
A procedure in which a thin needle called a spinal needle is put into the lower part of the spinal column to collect cerebrospinal fluid or to give drugs. Also called spinal tap.

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

lumpectomy  (lum-PEK-toh-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 biopsy  (… BY-op-see)
The removal of a small piece of lung tissue to be checked by a pathologist for cancer or other diseases. The tissue may be removed using a bronchoscope (a thin, lighted, tube-like instrument that is inserted through the trachea and into the lung). It may also be removed using a fine needle inserted through the chest wall, by surgery guided by a video camera inserted through the chest wall, or by an open biopsy. In an open biopsy, a doctor makes an incision between the ribs, removes a sample of lung tissue, and closes the wound with stitches.

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 metastasis  (...meh-TAS-tuh-sis)
Cancer that has spread from the original (primary) tumor to the lung.

Lupron  (LOO-pron)
A drug used to treat symptoms of advanced prostate cancer. It is also being studied in the treatment of other conditions and types of cancer. The active ingredient leuprolide blocks the body from making testosterone (a male hormone) and estradiol (a female hormone). It may stop the growth of prostate cancer cells that need testosterone to grow. Some brands of leuprolide are also used to treat early puberty in children and certain gynecologic conditions. Lupron is a type of gonadotropin-releasing hormone analog. Also called leuprolide acetate, Eligard, and Viadur.

lupus  (LOO-pus)
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 and 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. Also called LH-RH.

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

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 is a type of antidepressant agent and selective serotonin reuptake inhibitor (SSRI). 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 is a type of enzyme inhibitor. Also called pemetrexed disodium and Alimta.

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 being studied in the treatment of certain types of cancer, including non-Hodgkin lymphoma, breast, colon, lung, ovarian, and prostate. LY317615 blocks certain cell signaling pathways, and may prevent the growth of new blood vessels needed for tumors to grow. It is a type of serine threonine kinase inhibitor. Also called enzastaurin and enzastaurin hydrochloride.

LY335979  
A substance being studied in the treatment of cancer. LY335979 may help kill cancer cells that are resistant to anticancer drugs. Also called zosuquidar trihydrochloride.

LY353381 hydrochloride  (... HY-droh-KLOR-ide)
A substance being studied in the treatment of osteoporosis and breast cancer. LY353381 hydrochloride is made in the laboratory and binds to estrogen receptors in the body. It is a type of selective estrogen receptor modulator (SERM). Also called arzoxifene hydrochloride.

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 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 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  (LIM-fa-deh-NEK-toh-mee)
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  (lim-FA-deh-NAH-puh-thee)
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-gruh-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  (lim-FA-tik BAY-sin)
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-FA-tik ...)
The clear fluid that travels through the lymphatic system and carries cells that help fight infections and other diseases. Also called lymph.

lymphatic mapping  (lim-FA-tik ...)
The use of dyes and radioactive substances to identify lymph nodes that may contain tumor cells. Also called lymph node mapping.

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

lymphedema  (LIM-fuh-DEE-muh)
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  (LIM-foh-BLAST)
A lymphocyte that has gotten larger after being stimulated by an antigen. Lymphoblast also refers to an immature cell that can develop into a mature lymphocyte.

lymphoblastic lymphoma  (LIM-foh-BLAS-tik lim-FOH-muh)
An aggressive (fast-growing) type of non-Hodgkin lymphoma in which too many lymphoblasts (immature white blood cells) are found in the lymph nodes and the thymus gland. These lymphoblasts may spread to other places in the body. It is most common in teenagers and young adults and affects more males than females. It may be a T or B cell type. Also called precursor lymphoblastic lymphoma.

lymphocyte  (LIM-foh-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 infections and other diseases.

lymphocytic  (LIM-foh-SIH-tik)
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-foh-EH-pih-THEE-lee-OH-muh)
A type of cancer that begins in the tissues covering the nasopharynx (the upper part of the throat behind the nose).

lymphography  (lim-FAH-gruh-fee)
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-FOH-muh)
Cancer that begins in cells of the immune system. There are two basic categories of lymphomas. One kind is Hodgkin lymphoma, which is marked by the presence of a type of cell called the Reed-Sternberg cell. The other category is non-Hodgkin lymphomas, which includes a large, diverse group of cancers of immune system cells. Non-Hodgkin 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 and non-Hodgkin lymphomas can occur in children and adults, and prognosis and treatment depend on the stage and the type of cancer.

lymphomatoid granulomatosis  (lim-FOH-muh-toyd GRAN-yoo-loh-muh-TOH-sis)
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 lymphoma marked by abnormal levels of IgM antibodies in the blood and an enlarged liver, spleen, or lymph nodes. Also called Waldenström macroglobulinemia.

lymphoproliferative disorder  (LIM-foh-pruh-LIH-feh-RUH-tiv dis-OR-der)
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-foh-sin-TIH-gruh-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 colorectal cancer and certain other types of cancer, usually before the age of 50. Also called hereditary nonpolyposis colon cancer and HNPCC.

Lyrica  (LEER-ih-kuh)
A drug used to treat nerve pain caused by diabetes or herpes zoster infection and certain types of seizures. It is being studied in the prevention and treatment of nerve pain in the hands and feet of cancer patients given chemotherapy. Lyrica is a type of anticonvulsant. Also called pregabalin.

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.

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