SABCS 2013: Arimidex cuts breast cancer risk 53% in high risk women

A study of 4,000 women found that anastrozole, Anglo-Swedish drug major AstraZeneca’s (LSE: AZN) now off-patent breast cancer treatment Arimidex, is a new option to help prevent the disease, and can reduce the risk of breast cancer by 53% over five years when used as a preventative therapy in postmenopausal women who are at high risk of the disease.

Results were reported Thursday at that San Antonio Breast Cancer Symposium, and were also published in the per-reviewed journal The Lancet. The research was funded by Cancer Research UK and led by Queen Mary University of London. It was also supported by AstraZeneca and France’s Sanofi.

In the IBIS-II trial, which included 3,864 post-menopausal women at increased risk of breast cancer, 1,920 women were randomly assigned to receive anastrozole and 1,944 to placebo. After a median follow-up of 5·0 years (IQR 3·0-7·1), 40 women in the anastrozole group (2%) and 85 in the placebo group (4%) had developed breast cancer (hazard ratio 0·47, 95% CI 0·32-0·68, p<0·0001). The predicted cumulative incidence of all breast cancers after 7 years was 5·6% in the placebo group and 2·8% in the anastrozole group. 18 deaths were reported in the anastrozole group and 17 in the placebo group, and no specific causes were more common in one group than the other (p=0·836).