Letrozole, After Tamoxifen, Reduces Risk for Breast Cancer Recurrence

After surgery for hormone-receptor-positive breast cancer, a 5-year course of tamoxifen reduces risks for recurrence and for contralateral breast cancer. Continuing tamoxifen therapy beyond 5 years confers no additional benefit, yet breast cancer sometimes recurs after this interval. In this double-blind, randomized, partially manufacturer-supported trial, researchers examined whether the aromatase inhibitor letrozole prevents late recurrences. Aromatase inhibitors block the synthesis of estrogens from androgens.

More than 5000 postmenopausal women who had completed 5 years of tamoxifen therapy for hormone-receptor-positive breast cancer and who had no evidence of recurrence received either letrozole (2.5 mg daily) or placebo. The investigat…