Although its long-term effects continue to be studied, Tamoxifen was the first Selective Estrogen -Receptor Modulator (SERM) approved by the FDA in 1998 to help with the prevention of breast cancer in high-risk women. It is also used to help prevent a new formation of cancer in the other breast when a woman has already had breast cancer.

According to MedicineNet.com, a SERM is "a chemical that is designed to act like estrogen in certain tissue such as the bones and not like estrogen in other tissue such as the breast." SERMs exploit the benefits of estrogen , such as reducing osteoporosis , while avoiding the associated risks such as breast cancer.

How does Tamoxifen work?

Estrogen sensitive breast cancer cells need estrogen to develop and continue to grow. Tamoxifen blocks the estrogen receptors in these cancer cells so they cannot use the estrogen naturally produced in a woman's body. If the estrogen receptors are blocked, the cancer cells cannot grow and multiply. High-risk women who have had non-cancerous changes to their breasts are sometimes advised to go on Tamoxifen as a prophylactic measure to add to their regimen of breast cancer prevention.

What are some of the possible side effects?

One of the positive side effects of Tamoxifen is that it may help prevent fractures due to osteoporosis in postmenopausal women since it behaves like a weak estrogen in the bones. This provides a protective effect on the bones.

Some of the negative side effects of Tamoxifen are a slightly higher risk of developing uterine cancer or pulmonary embolism (blood clots), as well as symptoms that mimic menopause such as hot flashes, weight gain, vaginal dryness and irregular periods.

What is Raloxifene?

Another SERM approved by the FDA is Raloxifene, initially approved to prevent osteoporosis in postmenopausal women. Like Tamoxifen, "Raloxifene may reduce the risk of developing breast cancer in high risk women," according to MedicineNet.com. While Tamoxifen stimulates uterine cells, Raloxifene does not, leading to a lower risk of developing uterine cancer. Studies are currently being conducted that compare the benefits and limitations of Raloxifene and Tamoxifen in the prevention of breast cancer in high-risk women.

Prophylactic Mastectomy

Lastly, some women choose a prophylactic mastectomy as a preventive measure when they face a high risk of developing breast cancer. Studies have shown a 90% reduction in the development of breast cancer when this method is used. It is not completely fool proof, however, since some breast tissue may remain in areas such as the chest wall, underarms and even in the abdomen.

Women considering any of these preventative measures should consult their doctor and carefully weigh the risks along with the benefits before beginning any course of action.

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