Breast conservation (or breast sparing) surgery 
An operation that completely removes the breast cancer along with a rim of normal breast tissue around it. Most of the normal breast is saved. Surgery types are lumpectomy, quadrantectomy, and segmental mastectomy.

Cancer 
A term for many diseases in which abnormal cells divide without control. 

Chemoprevention 
The use of drugs, vitamins or other agents to prevent cancer in people who have precancerous conditions or a high risk of cancer, or to prevent the recurrence of cancer in people who have already been treated for it.

Chemotherapy 
Treatment with drugs to destroy cancer cells.  Chemotherapy is often used in addition to surgery or radiation to treat cancer when metastasis is proven or suspected, when the cancer has recurred, or when there is a strong likelihood that the cancer could recur.

Estrogen receptor 
This is a special type of protein found on some cancer cells. Estrogen attaches to it, and this can cause the cancer cells grow.

Hormone   
A chemical made by glands in the body. Hormones circulate in the bloodstream and control the actions of certain cells or organs. Some hormones can also be made in a laboratory.

Hormone receptor   
A protein on the surface of a cell that binds to a specific hormone. The hormone causes many changes to take place in the cell.

Hormone therapy 
Treatment of cancer by removing, blocking or adding hormones.

Invasive cancer 
A Cancer that has spread beyond the layer of tissue in which it developed and is growing into surrounding, healthy tissues.  Also called infiltrating cancer.

Localized cancer 
A cancerous growth that has not spread to other parts of the body.

Lumpectomy
Surgery to remove the tumor and a small amount of normal tissue around it.

Lymph node 
A rounded mass of lymphatic tissue that is surrounded by a capsule of connective tissue.  Also known as lymph gland.  Lymph nodes are spread out along lymphatic vessels and they contain many lymphocytes, which filter the lymphatic fluid.

Mastectomy 
This procedure ranges from simple mastectomy, where just the breast is removed, to radical mastectomy, where the entire breast and underarm lymph nodes are removed.

There are four general types of mastectomy:

• Subcutaneous Mastectomy
  Removal of the entire breast but leaving the nipple and areola (the pigmented skin around the nipple)
• Total (Simple) Mastectomy
  Removal of the whole breast but not the lymph nodes under the arm
• Modified Radical Mastectomy
  Removal of the whole breast and most of the lymph nodes under the arm
• Radical Mastectomy
  Removal of the chest wall muscles (pectorals) in addition to the breast and maxillary lymph nodes. This operation is rarely used today, and is mostly of historical interest

Metastasis
The spread of cancer from one part of the body to another.  Tumors formed from cells that have spread are called secondary tumors and contain cells that are like those in the original (primary) tumor.

Primary cancer 
The original cancer.  Primary cancer is usually named after the organ in which it starts (for example, cancer that starts in the breast is always breast cancer even if it metastasizes to other organs, such as bones or lungs).

Progesterone receptor negative (PR-)  
Breast cancer cells that do not have a protein (receptor molecule) to which progesterone will attach. Breast cancer cells that are PR- do not need the hormone progesterone to grow and usually do not respond to hormonal therapy.

Progesterone receptor positive (PR+)
Breast cancer cells that have a protein (receptor molecule) to which progesterone will attach. Breast cancer cells that are PR+ need the hormone progesterone to grow and will usually respond to hormonal therapy.

Prognosis 
The likely outcome or course of a disease; the chance of recovery.

Radiation therapy 
The use of high-energy radiation from x-rays, neutrons and other sources to kill cancer cells and shrink tumors.

Reconstruction after mastectomy 
This surgery recreates the breast for women who have undergone breast removal due to cancer or other disease. Reconstruction can be done with implants or with the patient's own tissue.

Recurrence 
The return of cancer, at the same site of origin (primary) or in another location, after it had disappeared.

Regional involvement 
The spread of cancer from the original tumor to nearby body parts.

Remission 
Disappearance of the signs and symptoms of cancer.  A remission may be temporary or permanent.

Secondary tumor 
A tumor that forms as a result of spread (metastasis) of cancer from its site of origin.

Stage 
The extent of a cancer within the body, including whether the disease has spread from the original site to other parts of the body.
Systemic Affecting the entire body.