LUMPECTOMY PLUS TAMOXIFEN OR ANASTROZOLE WITH OR WITHOUT WHOLE BREAST IRRADIATION IN WOMEN WITH FAVORABLE EARLY BREAST CANCER

Purpose: In women with favorable early breast cancer treated by lumpectomy plus tamoxifen or anastrazole, it remains unclear whether whole breast radiotherapy is beneficial. Methods and Material: Between January 1996 and June 2004, the Austrian Breast and Colorectal Cancer Study Group (ABCSG) randomly assigned 869 women to receive breast radiotherapy ± boost ( n = 414) or not ( n = 417) after breast-conserving surgery (ABCSG Study 8A). Favorable early breast cancer was specified as tumor size Results: The mean age was 66 years. Overall, there were 21 local relapses, with 2 relapses in the radiotherapy group (5-y rate 0.4%) vs. 19 in the no-radiotherapy group (5.1%), respectively ( p = 0.0001, hazard ratio 10.2). Overall relapses occurred in 30 patients, with 7 events in the radiotherapy group (5-y rate 2.1%) vs. 23 events in the no-radiotherapy group (6.1%) ( p = 0.002, hazard ratio 3.5). No significant differences were found for distant metastases and overall survival. Conclusion: Breast radiotherapy ± boost in women with favorable early breast cancer after lumpectomy combined with tamoxifen/anastrazole leads to a significant reduction in local and overall relapse.