547 Background: Initial adjuvant treatment with anastrozole has significant efficacy and tolerability advantages over tamoxifen in postmenopausal women with hormone-sensitive early breast cancer (EBC) (ATAC Trialists’ Group. Lancet 2005; 365: 60–62). The ARNO 95 study evaluated prospectively switching to anastrozole from tamoxifen after 2 years, compared with continuing tamoxifen therapy. Here, we present an interim efficacy and safety analysis. Methods: This was a prospective, randomized, open-label study conducted in 54 centers in Germany. Postmenopausal women (≤75 years) with hormone receptor-positive, invasive EBC, who had received 2 years of adjuvant tamoxifen without recurrence, were randomized to switch to anastrozole (1 mg/day) or continue on tamoxifen (20 or 30 mg/day) for a further 3 years. No adjuvant chemotherapy was given. The primary end point was disease-free survival (DFS; time to earliest occurrence of local or distant recurrence, new primary breast cancer, or death from any cause); secondary end points included overall survival (OS), safety, and tolerability. Data were analyzed using a log-rank test; a second analysis used a Cox proportional hazards model with covariates of age, tumor size, nodal status, grade, and type of surgery. Results: Overall, 979 patients (mean age 60 years; 74% node-negative; 97% hormone receptor-positive) were enrolled, 489 were randomized to switch to anastrozole, with 490 continuing on tamoxifen. Median follow-up was 30.1 months. Switching to anastrozole significantly improved DFS and OS compared with continuing on tamoxifen ( Table ). Fewer patients who switched to anastrozole reported serious adverse events (22.7%) compared with those who remained on tamoxifen (30.8%). Conclusions: Switching endocrine treatment improved DFS and OS in this well-defined population. Postmenopausal women with hormone-sensitive EBC who have already received 2 years’ adjuvant tamoxifen therapy should be switched to anastrozole. [Table: see text] [Table: see text]
Identification of patients with hormone receptor-positive breast cancer who need adjuvant tamoxifen therapy for more than 5 years
