Switching to anastrozole (ANA) vs continued tamoxifen (TAM) treatment of early breast cancer (EBC). Updated results of the Italian tamoxifen anastrozole (ITA) trial

Abstract

526 Background: We have previously shown that switching to ANA after 2–3 years of TAM is well tolerated and significantly improves event-free (EFS) and progression-free survival (PFS) of postmenopausal ebc (Breast Cancer Res Treat 82, 2003). Here we report on an additional analysis at a median follow-up time of 52 mos (1–80 mos). Methods: This was an open phase III trial comparing 5 years of TAM vs 2–3 years of TAM followed by 3–2 years of ANA (total duration of treatment: 5 years). PFS was the primary end point. EFS, OS and safety were secondary end points. Results: 448 node positive, ER positive patients were enrolled. At the time of the present analysis 87 events had occurred and 26 deaths. The first site of recurrence was the ipsilateral breast or the thoracic wall or the loco-regional nodes in 16 patients. Distant metastasis were the first site of recurrence in 47 patients; 19 patients developed second primaries (including 5 controlateral breast cancers). The Hazard Ratios of patients switched to ANA for EFS, PFS, local (l) PFS and distant (d)PFS are summarized in the table (Hazards of previous analysis are reported for comparison).17 women continued on TAM died as compared to 9 of those switched to ANA (HR: 0.52; 95% CI 0.23–1.17; p=0.1). The percentages of women developing at least one AE were 40% and 46% in the two groups respectively (p=0.2). However there were 6 endometrial cancers in the TAM group compared to 1 in the ANA group. Conclusions:Safety and clinical benefits of switching to ANA following 2 or 3 years of TAM are confirmed by this updated analysis. No significant financial relationships to disclose.