Hormonal therapy

The female hormones estrogen and progesterone play a role in the growth of breast cells. To make use of these hormones, breast cells normally have special receptors that permit the hormones to connect to the cells. Breast cancer cells that also have such receptors are known as "hormone-receptor positive." Reducing the amount of these hormones available to the cancer cells, the goal of hormonal therapy, may cause them to cease growing or die.

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After cancerous cells are surgically removed, they are tested for hormone receptors. If the tumor is receptor positive, hormonal therapy may lower the risk that cancer will recur in breast tissue or other parts of the body by either preventing the hormones from acting on the cell or lowering the amounts of hormones in the body. Patients with receptor-positive tumors usually experience fewer local recurrences and longer overall survival than those with receptor-negative tumors. Hormonal therapy has little effect on cancers that are not receptor positive.

Tamoxifen is the most widely used hormonal treatment for breast cancer in both premenopausal and postmenopausal women. It acts by blocking the ability of the hormones to attach to cancer cell receptors. Patients take a pill once a day for five years after their surgery. Side effects include night sweats and hot flashes, nausea, menstrual irregularity (when taken before menopause), vaginal discharge, and a dry, itchy vagina. Less common side effects can include depression, loss of appetite, weight gain, headache, and eye problems, such as cataracts. It can also increase the risk of strokes, pulmonary embolism, in which a blood clot lodges in the lung, and cancers of the uterus.

In postmenopausal women, another approach to hormonal therapy uses aromatase inhibitors, medications that reduce the amount of estrogen that the body produces. Patients generally take them orally each day for five years. Their effectiveness appears to match that of tamoxifen, but with lower risk of certain side effects, including blood clots and cancer of the uterus. However, women who take these medications may experience joint or muscle pain, and they appear to be at an increased risk of osteoporosis.

Another method of lowering the amount of estrogen in the body and slowing or stopping the growth and spread of breast cancer is surgically removing the ovaries. This approach may be suggested if your family history indicates that you are at elevated risk for ovarian as well as breast cancer.