and cardiac-specific mortality in a population-based cohort of elderly patients with nonmetastatic esophageal cancer. Materials/Methods: We identified 5,693 Medicare beneficiaries with esophageal cancer diagnosed between 2000 through 2011, including those receiving radiation (2,541), and those not receiving radiation (3,152). Medicare claims were used to identify radiation therapy and cardiac procedures as a surrogate for significant cardiac toxicity. Identified procedures included percutaneous coronary interventions, coronary artery bypass grafts, heart valve procedures, cardiac catheterizations, and pacemaker/ defibrillator procedures. Cause of death was used to determine cardiac specific mortality. Patients with a cardiac diagnosis or procedure in the year prior to their cancer diagnosis were considered high risk. Competing risk analyses, including cumulative incidence functions and multivariable Fine-Gray regression models, were used to evaluate the impact of radiation on these cardiac outcomes to account for the competing risk of death. Multivariable models controlled for patient, tumor, and treatment related variables. Results: Esophageal cancer patients receiving radiation had a substantial increase in both their risk of receiving a cardiac procedure and death due to cardiac causes compared to those not receiving radiation. The 5-year cumulative incidence of undergoing a cardiac procedure for patients treated with radiation versus those who were not was 9.1% (95% CI Z 7.9, 10.4) versus 5.2% (95% CI Z 4.4, 6.1). On multivariable analysis, patients treated with radiation had a 59% increased risk of receiving a cardiac procedure (subdistribution hazard ratio [SDHR] 1.59, 95% CI Z 1.23, 2.06, P < 0.001). Patients treated with radiation had a 50% increased risk of cardiac-specific mortality (SDHR Z 1.50, 95% CI Z 1.15, 1.96, P Z 0.003), and a decreased risk of cancer-specific mortality (SDHR Z 0.69, 95% CI Z 0.63, 0.74, P < 0.001). Conclusion: Radiation therapy, although effective in decreasing cancerspecific mortality, increases the risk of cardiac procedures and cardiacspecific mortality. This study can help radiation oncologists better understand and explain the risks and benefits of radiation to patients with esophageal cancer.