Key clinical point: The U.S. Preventive Services Task Force recommends against medication to prevent breast cancer in low-risk women, but says it may be considered for high-risk women.

Major finding: Tamoxifen, raloxifene, and aromatase inhibitors were associated with lower incidence of invasive breast cancer, with risk ratios of 0.69, 0.44, and 0.45, respectively, but adverse effects included thromboembolic events, endometrial cancer, and cataracts.

Study details: The researchers reviewed data from 46 studies, including 82 articles and more than 5 million individuals.

Disclosures: The research was funded by the Agency for Healthcare Research and Quality. Neither the task force researchers nor the editorialists reported relevant financial conflicts.