Anastrozole Halves Breast Cancer Incidence in High-Risk Postmenopausal Women

By Amy Orciari Herman

The aromatase inhibitor anastrozole cuts breast cancer incidence in half among high-risk postmenopausal women, according to an industry-supported trial in the Lancet.

Nearly 4000 postmenopausal women at increased risk (e.g., two or more first-degree relatives with breast cancer) were randomized to receive daily anastrozole or placebo for 5 years. During a median 5 years' follow-up, breast cancer developed significantly less often among anastrozole recipients (2% vs. 4%). The researchers estimate that 36 women would need to receive anastrozole to prevent one cancer during a 7-year period.

Adverse effects frequently seen with estrogen deprivation, including musculoskeletal and vasomotor symptoms, were more common in the anastrozole group.

The researchers say their results "strongly support" anastrozole for preventing breast cancer in high-risk women. A commentator, however, points to the side-effect profile, as well as the uncertain benefits on breast cancer mortality.