Cancer Dictionary – L
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.
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.
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.
large cell carcinoma (…KAR-sih-NOH-muh) Lung cancer in which the cells are large and look abnormal when viewed under a microscope.
lesion (LEE-zhun) An area of abnormal tissue. A lesion may be benign (noncancerous) or malignant (cancerous).
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.
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.
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).
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 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.
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.
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.
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.