New study: Anastrozole prevents breast cancer in high-risk women

December 13, 2013

Results of the IBIS II study, announced today at the San Antonio Breast Cancer Symposium, show that the drug anastrozole, an aromatase inhibitor, effectively reduces breast cancer incidence in high-risk postmenopausal women. The study, which began in 2003, involved nearly 4000 women selected on the basis of risk factors including family history of breast cancer, breast density and previous diagnosis of DCIS or LCIS.Half the women were given anastrozole, and the other half a placebo.

After a median follow-up of five years, 4% of women in the placebo group developed breast cancer, compared with 2% of the placebo group. The study found that the predicted cumulative incidence of all breast cancers after 7 years was 5.6% of the women in the placebo group, compared with only 2.8% of the anastrazole group. Side effects related to the treatment were low.

The study, published in The Lancet, shows that anastrozole is another potentially useful tool for women at high risk of breast cancer. Anastrozole is prescribed in New Zealand and is a relatively low-cost drug. Women with a high risk profile may want to discuss this study with their doctor.