Radiation Use and Long-Term Survival in Breast Cancer Patients With T1, T2 Primary Tumors and One to Three Positive Axillary Lymph Nodes

Background: For patients with Stage II breast cancer with one to three positive lymph nodes, controversy exists about whether radiation as a component of treatment provides a survival benefit. Methods and Materials: We analyzed data from patients with Stage II breast cancer with one to three positive lymph nodes diagnosed from 1988-2002 in the Surveillance, Epidemiology, and End Results registry and compared the outcome of 12,693 patients treated with breast-conservation therapy with radiation (BCT + XRT) with the 18,902 patients treated with mastectomy without radiation (MRM w/o XRT). Results: Patients treated with BCT + XRT were younger, were more likely to be treated in recent years of the study period, more commonly had T1 primary tumors, and had fewer involved nodes compared with those treated with MRM w/o XRT (p < 0.001 for all differences). The 15-year breast cancer-specific survival rate for the BCT + XRT group was 80% vs. 72% for the MRM w/o XRT group (p < 0.001). Cox regression analysis showed that MRM w/o XRT was associated with a hazard ratio for breast cancer death of 1.19 (p < 0.001) and for overall death of 1.25 (p < 0.001). The survival benefit in the BCT + XRT group was not limited to subgroups with high-risk disease features. Conclusions: Radiation use was independently associated with improved survival for patients with Stage II breast cancer with one to three positive lymph nodes. Because multivariate analyses of retrospective data cannot account for all potential biases, these data require confirmation in randomized clinical trials.