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Three Medications Beneficial in Breast Cancer Prevention

TUESDAY, Sept. 15 (HealthDay News) -- Three medications -- the selective estrogen receptor modulators tamoxifen and raloxifene, and tibolone, a drug not approved in the United States but used in many other countries to treat menopausal symptoms -- may reduce the risk for primary breast cancer. However, the three drugs are variously associated with an increased risk of thromboembolic events, endometrial cancer, or stroke, according to a study published online Sept. 15 in the Annals of Internal Medicine.

Heidi D. Nelson, M.D., of the Oregon Health and Science University in Portland, and colleagues conducted a systematic review of seven randomized controlled trials and one head-to-head trial.

Compared to placebo, the researchers found that tamoxifen, raloxifene, and tibolone significantly reduced the risk of invasive breast cancer (risk ratios, 0.70, 0.44, and 0.32, respectively). However, they found that tamoxifen and raloxifene are associated with an increased risk of thromboembolic events (risk ratios, 1.93 and 1.60, respectively), tamoxifen is a causal factor for endometrial cancer (risk ratio, 2.13), and that tibolone is a causal factor for strokes in older women.

"Before applying these findings to practice, clinicians must assure that women understand their individual risks for breast cancer and favorably balance these with the unwanted effects of risk reducing medications," the authors conclude.

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