Key Points Question What is the breast cancer–specific mortality (BCSM) risk over 20 years in men with stage I to III hormone receptor–positive breast cancer? Findings In this cohort study including 2836 men, the cumulative 20-year risk of BCSM was 12.4% for stage I, 26.2% for stage II, and 46.0% for stage III. Smoothed annual hazard estimates for BCSM revealed an increase in late hazard rates with each incremental node category, reaching a bimodal distribution in N3 and stage III.