Doses of intensity-modulated radiotherapy and its association with cardiac disease in esophageal cancer patients

BACKGROUND: No clear guidelines or available studies exist regarding the effects of intensity-modulated radiotherapy (IMRT) of esophageal cancer (EC) on the cardiovascular system. We therefore analyzed a wide range of cardiac vascular dosimetric parameters and clinical characteristics to assess the prognostic factors for EC patients treated with IMRT. METHODS: A total of 112 patients receiving IMRT at the Qianfoshan Hospital between July 2012 and May 2017 were retrospectively reviewed. The dose per fraction was 1.8–2.0 Gy, and the total dose range was 54–66 Gy. Kaplan-Meier analysis was used to estimate death due to heart disease. Univariate and multivariate logistic regression models were calculated to test for associations between patient characteristics and dose-volume histogram (DVH) parameters. A t-test and chi-squared or Fisher’s exact test was used to analyze the comparisons. RESULTS: The maximum and mean doses received by the heart were 57.34±13.51 and 24.83±11.40 Gy, respectively. Among the parameters examined, which included the maximum dose received by the heart, the mean dose received by the right and left ventricle (RV and LV), and the maximum dose received by the right atrium (RA), the mean dose received by the RV predicted survival and was included in our multivariate analysis. The results indicated that patients with basic heart disease who were undergoing concurrent radiochemotherapy were more likely to have cardiac disease. CONCLUSIONS: This is first study to examine the prognosis of cardiovascular vessels exposed to various radiation doses during the treatment of EC, the findings of which suggest that limiting radiation exposure may be an important measure in IMRT application. These findings of this study may provide theoretical support for prediction of radiation-induced heart disease (RIHD). Furthermore, to curb the risk of RIHD, the modality of chemotherapy also needs to be attentively monitored and managed.