The heart's exposure to radiation increases the risk of cardiac toxicity after chemoradiotherapy for superficial esophageal cancer: a retrospective cohort study

Chemoradiotherapy effectively treats superficial esophageal cancer and is optimal to preserve organs. However, late toxicity, particularly in cardiac diseases, obstructs clinical outcomes. We revealed the risk factors for cardiac event development post-chemoradiotherapy. Data from 80 patients who were diagnosed with submucosal invasive esophageal cancer without metastasis (confirmed using multiple modalities) and who underwent chemoradiotherapy between 2006 and 2014 were analyzed. Patients were 11% (9/80) female, and the median age and follow-up were 66.5 y and 73 mo, respectively. We calculated the individual radiation dose to the heart and analyzed relationships between the cardiac event occurrence rate and each clinical factor. The 5-y overall and recurrence-free survival rates were 74.6 and 62.4%, respectively. Among the total number of deaths, 34.6% was caused by esophageal cancer. During the follow-up, 13 patients developed severe cardiac events (ischemic heart diseases, n = 7; pericardial effusion, n = 3, atrial fibrillation, n = 1; and sudden death, n = 2). The significant risk factor for cardiac events post-chemoradiotherapy was the level of the heart's exposure to radiation, with higher exposure associated with greater occurrence. History of smoking, obesity, comorbidity, and history of cardiac disease were unrelated to cardiac event occurrence post-chemoradiotherapy. Chemoradiotherapy is a favorable intervention for superficial esophageal cancer. Reducing the radiation dose to the heart likely contributes to preventing cardiac toxicity post-chemoradiotherapy.