According to the results of a recent study published in the Journal of the National Cancer Institute, hormone therapy for postmenopausal women with a BRCA1 mutation does not appear to increase the risk of breast cancer.1
Inherited mutations in two genes—BRCA1 and BRCA2—have been found to greatly increase the lifetime risk of developing breast and ovarian cancer. Surgical oophorectomy (removal of ovaries) prior to menopause can substantially reduce this risk; however, the risk reduction is believed to be associated with the removal of ovarian hormones. So, there have been concerns about the subsequent use hormone therapy to cope with the symptoms of menopause because some studies have indicated that this could increase the risk of breast cancer.
Some hormone therapy regimens contain estrogen, while others are referred to as combined therapy and contain estrogen plus progesterone. A Women’s Health Initiative randomized trial found a statistically significant increase in the risk of breast cancer in association with the use of combined hormone therapy regimens.2 Ongoing studies continue to evaluate the risks and benefits of hormone therapy.
In this matched case-control study, researchers identified 236 matched pairs of postmenopausal BRCA1 mutation carriers who either had breast cancer or were considered a “control” (no breast cancer). They then evaluated the relationship between hormone therapy use and the risk of breast cancer. The results indicated that the use of hormone therapy did not increase the risk of developing breast cancer and in fact, in this particular population it was actually associated with a decreased risk.
While the results of this study are promising, much more research is needed in order to understand the relationship between hormone therapy and subsequent breast cancer risk. This particular study was done in a small group of women and there were many unknown factors, including the estrogen-receptor status of the cancers. Physicians and researchers continue to urge caution in using hormone therapy in women with BRCA1 mutations who are at a high risk for developing breast cancer.
1 Eisen, A., Lubinski, J., Gronwalk, J., et al. Hormone therapy and the risk of breast cancer in BRCA1 mutation carriers. Journal of the National Cancer Institute. 2008; 100: 1361-1367.
2 Rossouw, J., Anderson, G., Prentice R., et al. Risks and benefits of estrogen plus progestin in healthy post-menopausal women: principal results for the Women’s Health Initiative randomized controlled trial. JAMA. 2002; 288(3): 321-333.