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 <3 cm, Grading 1
or 2, negative lymph nodes, positive estrogen and/or
progesterone receptor status, and manageable by
breast-conserving surgery. Breast radiotherapy was performed
after lumpectomy with 2 tangential opposed breast fields
with mean 50 Gy, plus boost in 71% of patients with mean 10
Gy, in a median of 6 weeks. The primary endpoint was local
relapse-free survival; further endpoints were contralateral
breast cancer, distant metastases, and disease-free and
overall survival. The median follow-up was 53.8 months.
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.
