The aromatase inhibitor Arimidex has been found to reduce the risk of breast cancer by 53 percent in high-risk postmenopausal women. Aromatase inhibitors, which block the production of estrogen in postmenopausal women, are commonly used in the treatment of hormone receptor–positive breast cancer but may also have a role in breast cancer prevention—particularly in women at high risk of the disease.1
A study that included more than 3,000 postmenopausal women at high risk of breast cancer compared daily Arimidex with placebo, taken for five years for breast cancer prevention. After a median follow-up of five years, 40 women in the Arimidex group (2 percent) and 85 women in the placebo group (4 percent) had developed breast cancer. The researchers predicted that the overall incidence of all breast cancers after seven years was close to 6 percent in the placebo group compared with just under 3 percent in the Arimidex group.
1 Cuzick J, Sestak I, Forbes JF, et al. Anastrozole for prevention of breast cancer in high-risk postmenopausal women (IBIS-II): An international, double-blind, randomised placebo-controlled trial. The Lancet. 2014;383(9922):1041- 1048. doi:10.1016/S0140-6736(13)62292-8.