Lactation: Production of milk in the breast.

Large core biopsy: The surgical removal of a substantial sample of breast tissue for pathological examination.  Large core biopsy usually removes more breast tissue than vacuum-assisted biopsy but less than open surgical biopsy. The Advanced Breast Biopsy Instrumentation (ABBI) system made by U.S. Surgical is a large core biopsy procedure.

Latissimus dorsi flap procedure: A method of breast reconstruction that uses the long flat muscle of the back, by rotating it to the chest area.

Lesion: A wound, injury, or other damage to a body part. Breast tumors are often referred to as lesions.

LCIS: See lobular carcinoma in situ.

Leukine: Generic name, sargramostim. A drug used to treat neutropenic patients (those with a decreased white blood cell count). 

Limited breast surgery: Also called lumpectomy, segmental excision, or tylectomy. It removes the breast cancer and a small amount of tissue around the cancer, but preserves most of the breast. It is almost always combined with axillary lymph node removal and is followed by radiation therapy. (See also lumpectomy).

Linear accelerator: A machine used in radiotherapy to treat cancer. A linear accelerator generates gamma rays and electron beams which are focused on the cancerous tissue.

Lobe: A group of lobules (glands) in the breast.  The breast contains 15 to 24 lobes.

Lobular carcinoma in situ (LCIS): A very early type of breast cancer that develops within the milk-producing glands (lobules) of the breast and does not penetrate through the wall of the lobules. Though technically a Stage 0 breast cancer (the earliest stage, many physicians do not classify LCIS as a cancer. However, LCIS places a woman at increased risk of developing an invasive breast cancer later in life, which can occur in either breast.

Lobule: Gland in the breast responsible for producing milk.

Localized breast cancer: A cancer that starts in the breast and is confined to the breast.

Lump: Any kind of mass in the breast or elsewhere in the body.  Also called nodule.

Lumpectomy: Surgery to remove the breast tumor and a small margin of surrounding normal tissue. (See also breast conservation therapy, two-step procedure).

Lymph: Clear fluid that passes within the lymphatic system and contains cells known as lymphocytes. These cells are important in fighting infections and may also have a role in fighting cancer.

Lymph nodes: Small bean-shaped structures of immune system tissue such as lymphocytes, located along lymphatic vessels. They remove waste and fluids from lymph and help fight infections. Also called lymph glands. (See also lymph, lymphatic system). 

Lymph node removal: Surgery to remove some or all of the lymph nodes.  See axillary node dissection, sentinel node biopsy.

Lymphatic system: The tissues and organs (including bone marrow, spleen, thymus, and lymph nodes) 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 the body's immune system. Invasive cancers sometimes penetrate the lymphatic vessels and metastasize (spread) to lymph nodes.

Lymphedema: A side effect that occurs in some patients after breast cancer treatment; more likely if some or all of the axillary lymph nodes are removed. Swelling in the arm caused by excess fluid that collects after lymph nodes and vessels are removed by surgery or treated by radiation. This condition is usually persistent.

Lymphoma: A cancer of lymphocytes (a type of white blood cell) that usually develops in the lymph nodes. About 5% of cancers are lymphomas. The two main types of lymphomas are Hodgkin's disease and non-Hodgkin's lymphomas. Lymphoma can occur as a result of some types of cancer therapies.

Updated: August 2006