In 1971 we began a randomized trial to compare alternative local and regional treatments of breast cancer, all of which employ breast removal. Life-table estimates were obtained for 1665 women enrolled in the study for a mean of 126 months. There were no significant differences among three groups of patients with clinically negative axillary nodes, with respect to disease-free survival, distant-disease--free survival, or overall survival (about 57 per cent) at 10 years. The patients were treated by radical mastectomy, total ("simple") mastectomy without axillary dissection but with regional irradiation, or total mastectomy without irradiation plus axillary dissection only if nodes were subsequently positive. Similarly, no differences were observed between patients with clinically positive nodes treated by radical mastectomy or by total mastectomy without axillary dissection but with regional irradiation. Survival at 10 years was about 38 per cent in both groups. Our findings indicate that the location of a breast tumor does not influence the prognosis and that irradiation of internal mammary nodes in patients with inner-quadrant lesions does not improve survival. The data also demonstrate that the results obtained at five years accurately predict the outcome at 10 years. We conclude that the variations of local and regional treatment used in this study are not important in determining survival of patients with breast cancer.