Prevention and Lifestyle Factors

In spite of some rumors published in the popular press, antiperspirants or use of deodorants after shaving have not been linked with any higher risk for breast cancer.

Tamoxifen and Other SERMs. Drugs known as selective estrogen-receptor modulators (SERMs) act like estrogen in some tissues but behave like estrogen blockers (anti-estrogens) in others. Tamoxifen (Nolvadex) is the most studied of these drugs. It is currently used to treat breast cancer and is the only drug to date approved for prevention. Evidence strongly suggests that it halves the risk for estrogen receptor-positive cancers in high-risk women, including those with BRCA2 mutations (although possibly not BRCA1). It also helps prevent recurrence in women who have been treated for breast cancers. However, it has no protective effects against estrogen receptor-negative cancers.

Raloxifene (Evista), another SERM, also protects against breast cancer and osteoporosis and has a lower risk than tamoxifen of causing uterine cancer. Results from a major comparison trial, Study of Tamoxifen and Raloxifene (STAR), were published in 2006. This study enrolled nearly 20,000 postmenopausal women at high risk for breast cancer. The data indicated that raloxifene worked as well as tamoxifen in reducing the risk of invasive breast cancer, and had a lower risk of causing blood clots. Side effects varied between the two drugs. Tamoxifen caused problems with gynecological symptoms, hot flashes, leg cramps, and bladder control. Women who received raloxifene tended to experience more musculoskeletal problems, sexual dysfunction, and weight gain.

Although the STAR study suggested that raloxifene is less likely to cause blood clots than tamoxifen, a 2006 study in the New England Journal of Medicine indicated that raloxifene carries its own risks for blood clots and fatal strokes. The researchers suggested that raloxifene may not be a safe choice for women at high risk of heart disease.

Tamoxifen and raloxifene are not recommended as prevention for women at low risk for breast cancer or its recurrence. Women at high risk for breast cancer should discuss with their doctors the risks and benefits of SERMs.