Reducing the Risk of Invasive Breast Cancer

The annual meeting of the American Society of Clinical Oncology (ASCO) was held last week in Chicago. I always look forward to this time of year because the ASCO meeting provides a mechanism for researchers to disseminate their yet-to-be published study results. Although a dizzying number of study findings are being reported for the first time, there are always a few studies that catch my eye (as well as the eyes of the media). This year, it’s the study that found that exemestane (also known as Aromasin®, manufactured by Pfizer Inc.) reduced the risk of developing breast cancer by 65% in post-menopausal women at high risk for breast cancer.

In this study, 4,560 post-menopausal women at high risk for breast cancer were randomized to receive exemestane or a placebo. Eleven women who received exemestane and 32 women who received a placebo developed invasive breast cancer. Of note, however, is that the median follow-up time for the study was 3 years; therefore, a limitation of the study is the duration of follow-up.

Exemestane also has fewer side effects than agents used in the past to prevent breast cancer, such as tamoxifen. The researchers found that side effects of exemestane include hot flashes, sweating, insomnia and fatigue, and there was a slight increase in the women’s risk of osteopenia. In media reports and interviews, oncologists have expressed excitement about this study’s findings, and note that exemestane may be an alternative to tamoxifen or a bilateral prophylactic mastectomy.