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Glossary - L

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  • Laboratory study

    (LA-bruh-tor-ee STUH-dee)

    Research done in a laboratory. A laboratory study may use special equipment and cells or animals to find out if a drug, procedure, or treatment is likely to be useful in humans. It may also be a part of a clinical trial, such as when blood or other samples are collected. These may be used to measure the effect of a drug, procedure, or treatment on the body.

  • Lactate dehydrogenase

    (LAK-tayt dee-hy-DRAH-jeh-nays)

    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.

  • Laser

    (LAY-zer)

    A device that forms light into intense, narrow beams that may be used to cut or destroy tissue, such as cancer tissue. It may also be used to reduce lymphedema (swelling caused by a buildup of lymph fluid in tissue) after breast cancer surgery. Lasers are used in microsurgery, photodynamic therapy, and many other procedures to diagnose and treat disease.

  • Laser surgery

    (LAY-zer SER-juh-ree)

    Treatment that uses intense, narrow beams of light to cut and destroy tissue, such as cancer tissue. Laser therapy may also be used to reduce lymphedema (swelling caused by a buildup of lymph fluid in tissue) after breast cancer surgery.

  • Late effect

    (layt eh-FEKT)

    A health problem that occurs months or years after a disease is diagnosed or after treatment has ended. Late effects may be caused by cancer or cancer treatment. They may include physical, mental, and social problems and second cancers.

  • Late-stage cancer

    (LAYT-stayj KAN-ser)

    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

    (LAY-tent)

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

  • Laxative

    (LAK-suh-tiv)

    A substance that promotes bowel movements.

  • Lesion

    (lee-zhun)

    A change in body tissue; sometimes used as another word for tumor.

  • 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.

  • Leucopenia

    Decrease in the white blood cell count, often a side effect of chemotherapy.

  • 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 of the blood or blood-forming organs. If you have leukemia, you may have a noticeable increase in white blood cells (leukocytes).

  • Leukocytes

    (LOO-koh-site)

    A type of blood cell that is made in the bone marrow and found in the blood and lymph tissue. Leukocytes are part of the body’s immune system. They help the body fight infection and other diseases. Types of leukocytes are granulocytes (neutrophils, eosinophils, and basophils), monocytes, and lymphocytes (T cells and B cells). Checking the number of leukocytes in the blood is usually part of a complete blood cell (CBC) test. It may be used to look for conditions such as infection, inflammation, allergies, and leukemia. Also called WBC and white blood cell.

  • Leukocytosis

    (loo-ko-sigh-toe-sis)

    Having more than the usual number of white blood cells.

  • Levels of evidence

    (LEH-vulz ... 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.

  • Li-Fraumeni syndrome

    (lee-FRAH-meh-nee SIN-drome)

    A rare, inherited disorder that is caused by mutations (changes) in the TP53 gene. Having Li-Fraumeni syndrome increases the risk of developing many types of cancer. Cancers often develop at an early age, and more than one type of cancer may occur in the same person. Li-Fraumeni syndrome is a type of hereditary cancer syndrome. Also called LFS.

  • Lidocaine

    (LY-doh-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.

  • Lifetime risk

    (LIFE-time risk)

    A measure of the risk that a certain event will happen during a person’s lifetime. In cancer research, it is usually given as the likelihood that a person who is free of a certain type of cancer will develop or die from that type of cancer during his or her lifetime. For example, a woman with no known risk factors for breast cancer has a lifetime risk of developing breast cancer of about 12%. This means one out of every eight women will develop breast cancer during her lifetime.

  • 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.

  • Limb-sparing surgery

    lim-SPAYR-ing SER-juh-ree

    Surgery to remove a tumor in a limb (arm or leg) without removing the whole limb. The bone and tissue around the tumor may also be removed, and an implant may be used to replace the part of the limb removed. Limb-sparing surgery is done to help save the use and appearance of the limb. It is used to treat cancers of the bone and soft tissue. Also called limb-salvage surgery.

  • Line

    A narrow short synthetic tube that is inserted approximately one inch into a vein to provide temporary intravenous access for the administration of fluid, medication, or nutrients.

  • Liquid biopsy

    (LIH-kwid BY-op-see)

    A test done on a sample of blood to look for cancer cells from a tumor that are circulating in the blood or for pieces of DNA from tumor cells that are in the blood. A liquid biopsy may be used to help find cancer at an early stage. It may also be used to help plan treatment or to find out how well treatment is working or if cancer has come back. Being able to take multiple samples of blood over time may also help doctors understand what kind of molecular changes are taking place in a tumor.

  • Liver

    (LIH-ver)

    An organ in your body which performs many complex functions necessary for life. These include processes related to digestion, production of certain proteins, and elimination of many of the body's waste products.

  • Liver cancer

    (LIH-ver KAN-ser)

    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.

  • Local anesthetic

    A medication given by injection into a part of your body to prevent pain in the area without putting you to sleep.

  • Local cancer

    (LOH-kul KAN-ser)

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

  • Local therapy

    (LOH-kul THAYR-uh-pee)

    Treatment that is directed to a specific organ or limited area of the body, such as the breast or an abnormal growth on the skin. Examples of local therapy used in cancer are surgery, radiation therapy, cryotherapy, laser therapy, and topical therapy (medicine in a lotion or cream that is applied to the skin).

  • Localization

    (LOH-kuh-lih-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

    (LOH-kuh-lized)

    In medicine, describes disease that is limited to a certain part of the body. For example, localized cancer is usually found only in the tissue or organ where it began, and has not spread to nearby lymph nodes or to other parts of the body. Some localized cancers can be completely removed by surgery.

  • Long-term side effects

    (... eh-FEKT)

    A problem that is caused by a disease or treatment of a disease and may continue for months or years. Long-term side effects of cancer treatment include heart, lung, kidney, or gastrointestinal tract problems; pain, numbness, tingling, loss of feeling, or heat or cold sensitivity in the hands or feet; fatigue; hearing loss; cataracts; and dry eyes or dry mouth.

  • Long term survivor

    If you are 5 years from the last sign of disease and at least 2 years off therapy.

  • Low-grade

    (loh-grayd)

    A term used to describe cells and tissue that look almost normal under a microscope. Low-grade cancer cells look more like normal cells and tend to grow and spread more slowly than high-grade cancer cells. Cancer grade may be used to help plan treatment and determine prognosis. Low-grade cancers usually have a better prognosis than high-grade cancers and may not need treatment right away.

  • Lumbar puncture

    LUM-bar PUNK-cher

    A procedure in which a thin needle is placed in your spinal canal to withdraw a small amount of spinal fluid or to give medicine into the central nervous system through the spinal fluid. If you have leukemia, this fluid is tested for the possible presence of ""blasts"" cells as well as other elements.

  • Lung metastasis

    (...meh-TAS-tuh-sis)

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

  • Lymph

    limf

    Clear fluid that flows through the lymphatic vessels and contains cells known as lymphocytes. These cells are important in fighting infections and may also have a role in fighting cancer.

  • Lymph nodes

    limf nodes

    A small bean-shaped structure that is part of the body’s immune system. Lymph nodes filter substances that travel through the lymphatic fluid, and they contain lymphocytes (white blood cells) that help the body fight infection and disease. There are hundreds of lymph nodes found throughout the body. They are connected to one another by lymph vessels. Clusters of lymph nodes are found in the neck, axilla (underarm), chest, abdomen, and groin. For example, there are about 20-40 lymph nodes in the axilla. Also called lymph gland.

  • Lymphatic system

    lim-FA-tik SIS-tem

    The tissues and organs (including lymph nodes, spleen, thymus, and bone marrow) that produce and store lymphocytes (cells that fight infection) and the channels that carry the lymph fluid. The entire lymphatic system is an important part of your body's immune system. Invasive cancers sometimes penetrate your lymphatic vessels (channels) and spread (metastasize) to your lymph nodes.

  • 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.

  • Lymphocyte

    LIM-foh-site

    A type of immune cell that is made in the bone marrow and is found in the blood and in lymph tissue. The two main types of lymphocytes are B lymphocytes and T lymphocytes. B lymphocytes make antibodies, and T lymphocytes help kill tumor cells and help control immune responses. A lymphocyte is a type of white blood cell.

  • Lymphocytes

    LIM-foh-site

    A type of immune cell that is made in the bone marrow and is found in the blood and in lymph tissue. The two main types of lymphocytes are B lymphocytes and T lymphocytes. B lymphocytes make antibodies, and T lymphocytes help kill tumor cells and help control immune responses. A lymphocyte is a type of white blood cell.

  • Lymphocytic

    (LIM-foh-SIH-tik)

    Refers to lymphocytes (a type of white blood cell).

  • Lymphocytosis

    Having an excess of lymphocytes.

  • Lymphoma

    lim-FOH-muh

    Cancer of the lymphatic system, a network of thin vessels and nodes throughout the body. Lymphoma involves a type of white blood cells called lymphocytes. The two main types of lymphoma are Hodgkin's disease and non-Hodgkin's lymphoma. The treatment methods for these two types of lymphomas are very different.