Exemestane Reduces Breast Cancer Risk in High-Risk Postmenopausal Women
Adapted from the NCI Cancer Bulletin.

The list of drugs that have been shown to reduce a woman's chance of developing breast cancer can now be expanded from two to three. Clinical trial results presented at the 2011 American Society of Clinical Oncology (ASCO) annual meeting showed that the aromatase inhibitor exemestane (Aromasin®)—commonly used to treat early and advanced-stage breast cancer—substantially reduced the risk of invasive breast cancer in postmenopausal women at high risk of developing the disease.

The findings were also published online June 4, 2011, in the New England Journal of Medicine (NEJM).

At 3 years of follow-up, women who took exemestane were 65 percent less likely than women who took a placebo to develop breast cancer. This is the largest reduction in risk seen in any of the four large breast cancer prevention trials that have been conducted to date. In previous trials, daily use of tamoxifen or raloxifene reduced breast cancer risk by approximately 50 percent and 38 percent, respectively, after 5 years of follow-up; both drugs were eventually approved by the Food and Drug Administration (FDA) to reduce breast cancer risk.