Impact of Postoperative Radiotherapy on the Risk of Ischemic Heart Disease and Survival in Patients with Ductal Carcinoma In Situ: A Nationwide Claims-Based Cohort Study

Postoperative RT did not increase the long-term risk of IHD but was associated with improved OS in patients with DCIS. These findings provide population-based evidence supporting the cardiac safety and oncologic efficacy of postoperative RT, while recognizing that unmeasured differences in health behavior or medical care utilization could have contributed to the observed survival benefit.