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A small channel in the breast through which milk passes from the lobules, where the milk is made, to the nipple.

Ductal carcinoma in situ (DCIS, also called intraductal carcinoma)

Abnormal cancer cells that involve only the lining of milk duct. The cells cannot spread outside the duct to other tissues in the breast or beyond the breast.

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A female hormone manufactured primarily by the ovaries.

Estrogen or progesterone receptor test

Laboratory tests done to determine if breast cancer will respond to tamoxifen or other hormonal therapies.

Estrogen replacement therapy

Estrogen in pill or patch form, which is given after menopause to reduce menopause symptoms. Prolonged use has been linked to higher risk for breast cancer.

Excisional biopsy

Surgical removal of an entire lump.

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Fine needle aspiration

A biopsy that uses a thin needle to remove fluid from a cyst or a cluster of cells from a solid lump.

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A scale based on the cellular structure of the tumor to determine the aggressiveness of a cancer. Grade 1 is least aggressive, Grade 3 is most aggressive. The grade is determined by the pathologist who examines the cells under a microscope.

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A form of chemotherapy designed to destroy breast cancer cells that over express an abnormal gene called HER2.

Hormonal therapy

The use of hormones to treat cancer patients by removing, blocking, or adding to the effects of a hormone on an organ or part of the body. Also called endocrine therapy.

Hormone receptor tests

Lab tests that determine if a breast cancer depends on female hormones (estrogen and progesterone) for growth. A high level of hormone receptors may mean that hormones help the cancer grow.

Hormone replacement therapy

Often referred to as HRT, hormones (estrogen and/or progesterone) may be given to postmenopausal women to alleviate symptoms of menopause. Long-term usage has been shown to be a risk factor for breast cancer.


Substances produced by various glands that affect the function of body organs and tissues.


An abnormal overgrowth of cells.

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A silicone or saline-filled sac inserted under the chest muscle to restore breast shape.

In situ

Very early or noninvasive abnormal cells that are confined to the ducts or lobules in the breast; also known as DCIS (ductal carcinoma in situ) or LCIS (lobular carcinoma in situ).

Infiltrating or invasive breast cancer:

Cancer that has the ability to spread to nearby tissue, lymph nodes in the armpit, or other distant parts of the body.

Inflammatory breast cancer

A type of breast cancer in which the breast looks red and swollen and feels warm. The skin of the breast may show a pitted appearance. The redness and warmth occur because the cancer cells block the lymph vessels in the skin.

Intraductal carcinoma

Abnormal cells that are contained within the milk duct and have not spread outside the duct. Also known as DCIS (ductal carcinoma in situ).

Invasive breast cancer

Cancer that has the ability to spread into surrounding, healthy tissues, lymph nodes, or distant parts of the body. Also called infiltrating cancer.

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An area of abnormal tissue change.

Lobe, lobule

Located at the end of a breast duct, the part of the breast where milk is made. Each breast contains 15 to 20 sections, called lobes, each with many smaller lobules.

Lobular carcinoma in situ (LCIS)

Abnormal cells in the lobules of the breast; a sign that a woman is at an increased risk of developing breast cancer anywhere, in either breast.


Surgical removal of breast cancer and a small amount of normal tissue surrounding the cancer.

Lymph nodes

Small bean-shaped organs that remove waste from body tissues and filter the fluids that help the body fight infection. Lymph nodes under the arm drain fluid from the chest and arm. During surgery, some underarm lymph nodes are usually removed to determine the stage of breast cancer.


Swelling, or accumulation of lymphatic fluid in the arm that may occur following treatment for breast cancer. It occurs because the lymph nodes were removed to stage breast cancer and/or damaged by radiation therapy.

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This glossary is largely an excerpt from An Informational Guide to Breast Cancer, August 2005, HCA, Inc., Nashville, Tennessee. Printed here with permission. Reviewed by Joanne Hindle, RN, MS, NP-C, OCN. We thank HCA and these individual contributors: Connie Carson, Ph.D., Healthcare Consultant, Littleton, Colorado; Rebecca Knight, MD, FACS, General Surgeon, Foothills Surgical Associates, Wheat Ridge, Colorado; Francene Mason, M.D., Medical Oncologist, Boulder, Colorado; Susan Lasker-Hertz, RN, MSN, CHPN, Director of Clinical Services, Denver Hospice, Denver, Colorado; Barbara Schwartzberg, M.D., F.A.C.S., Breast Cancer Surgeon, HealthONE, Denver, Colorado; and Dev Paul, D.O., Ph.D., Medical Oncologist, Rocky Mountain Cancer Centers, Denver, Colorado.