A growth factor that plays an important role in the regulation of cell growth, proliferation, and differentiation by binding to its receptor EGFR. It’s importance in breast cancer relates to it’s role in the uncontrolled growth of cancer by repeated cell division. Much research in treatment of cancer is currently focused on inhibiting the “receptor” where EGF attaches to the cancer cell wall. By blocking the receptor, a drug can theoretically prevent EGF from stimulating cancer cell growth.

Estrogen is a female hormone produced by the ovaries, and to a lesser degree by the adrenal glands, liver, and fat cells. Estrogen deficiency can lead to osteoporosis.

A protein present in breast and other cells that has an affinity for estrogen in the circulation. The binding of estrogen causes a change in the receptor shape which then turns on certain metabolic processes that stimulates cellular growth. While this is a good outcome in normal breast development, in cancer cells, many of which have increased numbers of estrogen receptors, the stimulation caused by estrogen can lead to enhanced cancer growth and spread. In newly diagnosed breast cancer, estrogen receptor (ER) is routinely measured in the cancer cells to help decide about certain treatment options. If the cancer is ER positive (+), treatment with estrogen blocking or inhibiting drugs is typically added to the overall treatment plan. Options include the use of an “aromatase inhibitor”, or tamoxifen.

Pertaining to the act of excision, of removal by surgery. An excisional biopsy is one in which the lesion is removed by the biopsy. From the Greek ektome meaning excision.

A biopsy in which an entire biopsy in which an entire lesion, is removed. A excisional biopsy is in contrast to an incisional biopsy in which only a sample of tissue is cut into (incised) and removed.

Radiation therapy using a machine to aim high-energy rays at a tumor in the breast (or other part of the body). You can think of it as like having a mammogram, except that the dose of radiation is much much higher.