Characteristics of cardiac toxicity after definitive radiation therapy for thoracic esophageal cancer in Japanese patients

In recent years, there has been growing interest in cardiac toxicity following radiation therapy (RT) for esophageal cancer; however, detailed incidence and risk factors in Japanese patients remain unclear. The purpose of this study was to clarify the incidence, timing, risk factors, and dose-volume relationships of multiple cardiac toxicities, including pericardial effusion, heart failure, arrhythmia, cardiac valve disease and acute coronary syndrome. We retrospectively analyzed patients of thoracic esophageal cancer without distant metastasis who were treated with curative RT at our hospital between 2007 and 2020. Cardiac toxicity events were graded according to common terminology criteria for adverse events v5.0. Association between cardiac dose-volume parameters and grade 2 or higher toxicity was analyzed using logistic regression analysis. The analysis included 250 patients, with a median follow-up period of 21 months. The 2-year cumulative incidence of grade 2 or higher pericardial effusion, heart failure, arrhythmia, and acute coronary syndrome were 36.6%, 0.4%, 1.4%, and 1.3%, respectively. Logistic regression analysis identified the volume of the whole heart receiving 30Gy as a significant risk factor for grade 2 pericardial effusion (OR, 1.03; 95% confidence interval [CI], 1.01-1.04; P < 0.01) and grade 2 arrhythmia (OR, 1.10; 95%CI, 1.02-1.18; P = 0.01). We reported detailed profile of cardiac toxicity in Japanese patients who received curative RT for esophageal cancer. Reducing cardiac radiation dose may reduce the risk of pericardial effusion and arrhythmia.