There are certain hormones that can attach to breast cancer cells and affect their ability to multiply. The purpose of endocrine therapy, formerly called hormone therapy, is to add, block, or remove hormones.
With breast cancer, the female hormones estrogen and progesterone can promote the growth of some breast cancer cells. Therefore in some patients, endocrine therapy is given to block the body's naturally occurring estrogen to slow or stop the cancer's growth.
There are two types of hormone therapy for breast cancer.
Drugs that inhibit estrogen and progesterone from promoting breast cancer cell growth.
Drugs or surgery to turn off the production of hormones from the ovaries.
Do not confuse the term hormone therapy that is used for treating women with breast cancer with hormone replacement therapy that is typically used by postmenopausal women. Hormone therapy for cancer treatment, endocrine therapy, stops hormones from getting to breast cancer cells. Hormone therapy for postmenopausal women without cancer -- called "hormone replacement therapy" -- adds more hormones to your body to counter the effects of menopause.
Who Gets Endocrine Therapy for Breast Cancer?
As part of the diagnosis process, tests are done to determine if the breast cancer cells have estrogen or progesterone receptors. If so, that means that growth of the cancer can be stimulated with these hormones. If a cancer is found to have these receptors, endocrine therapy is recommended as part of the treatment plan.
What Hormone Therapy Drugs Are Used for Breast Cancer?
There are several common hormone therapy drugs used for breast cancer:
Breast Cancer and Tamoxifen
Tamoxifen is a pill that has been used for over 30 years to treat breast cancer. It was first used in metastatic breast cancer (cancer that spread) because it slowed or stopped the growth of cancer cells in the body. Tamoxifen also decreases the chance that some early-stage breast cancers will recur in premenopausal or post menopausal women and it can reduce the risk of cancer developing in the unaffected breast.
In addition, tamoxifen may offer an alternative to watchful waiting or prophylactic (preventative) mastectomy for women at high risk for developing breast cancer.