Extending Aromatase Inhibitor Therapy for Early Breast Cancer

In an earlier trial, administration of the aromatase inhibitor (AI) letrozole for 5 years — after about 5 years of adjuvant tamoxifen therapy — significantly improved disease-free survival (DFS) compared with placebo in postmenopausal women with early breast cancer (N Engl J Med 2003; 349: 1793). To determine whether extending the duration of letrozole for an additional 5 years would lower risk for recurrence further, these investigators conducted a randomized, double-blind trial that involved 1918 postmenopausal patients with hormone-receptor–positive early-stage disease who had received 4.5 to 6.0 years of adjuvant AI therapy, preceded (in most women) by tamoxifen. Within 2 years of completing AI therapy, disease-free patients were random…