A randomized trial of long term adjuvant tamoxifen plus postoperative radiation therapy versus radiation therapy alone for patients with early stage breast carcinoma treated with breast-conserving surgery. Stockholm Breast Cancer Study Group.

At 10 years, the overall survival was 90% for the tamoxifen group and 88% for the control group. The event free survival at 10 years was 80% for the tamoxifen group and 70% for the control group (P=0.03). Tamoxifen reduced the overall rate of ipsilateral (hazard ratio=0.4, 95% confidence interval [CI]=0.2-0.9, P=0.02) and contralateral breast tumor recurrences (hazard ratio=0.4, 95% CI=0.1-1.1, P=0.06). Trends toward a reduced number of distant metastases (hazard ratio=0.6, 95% CI=0.3-1.2, P=0.1) and deaths due to breast carcinoma (hazard ratio=0.5, 95% CI=0.2-1.2, P=0.1) also were observed. CONCLUSIONS. The addition of tamoxifen to radiotherapy for postmenopausal, lymph node negative breast carcinoma patients treated with breast-conserving surgery resulted in a reduced rate of ipsilateral and contralateral breast tumor recurrences. The avoidance of salvage mastectomies, reexcisions, and new contralateral malignancies justifies the use of tamoxifen even in the treatment of patients with a 10-year survival rate of 90%.