We determined the effect of breast irradiation plus tamoxifen on disease-free survival and local relapse in women 50 years of age or older who had T1 or T2 node-negative breast cancer.

Between December 1992 and June 2000, 769 women with early breast cancer (tumor diameter, 5 cm or less) were randomly assigned to receive breast irradiation plus tamoxifen (386 women) or tamoxifen alone (383 women). The median follow-up was 5.6 years.

The rate of local relapse at five years was 7.7 percent in the tamoxifen group and 0.6 percent in the group given tamoxifen plus irradiation (hazard ratio, 8.3; 95 percent confidence interval, 3.3 to 21.2; P<0.001), with corresponding five-year disease-free survival rates of 84 percent and 91 percent (P=0.004). A planned subgroup analysis of 611 women with T1, receptor-positive tumors indicated a benefit from radiotherapy (five-year rates of local relapse, 0.4 percent with tamoxifen plus radiotherapy and 5.9 percent with tamoxifen alone; P<0.001). Overall, there was a significant difference in the rate of axillary relapse at five years (2.5 percent in the tamoxifen group and 0.5 percent in the group given tamoxifen plus irradiation, P=0.049), but no significant difference in the rates of distant relapse or overall survival.

As compared with tamoxifen alone, radiotherapy plus tamoxifen significantly reduces the risk of breast and axillary recurrence after lumpectomy in women with small, node-negative, hormone-receptor-positive breast cancers.