Association between Radiotherapy and Anatomic Severity of Coronary Artery Disease: A Propensity Score Matching Comparison Among Adult-Onset Thoracic Cancer Survivors

<b><i>Objective:</i></b> To investigate the association between radiotherapy and anatomic severity of coronary artery disease (CAD) using the SYNTAX scores (SXscores) of coronary angiograms in adult-onset thoracic cancer survivors. <b><i>Methods:</i></b> A total of 152 patients who previously had thoracic cancer and underwent coronary angiography between 2010 and 2016 were examined. Propensity score matching (PSM) was used to identify 27 well-matched pairs of patients. Characteristics and coronary angiograms were collected from each patient. Coronary artery abnormalities were assessed using SXscores of coronary angiograms. <b><i>Results:</i></b> Among the 152 patients, the SXscores and percentage of high SXscores were higher in the radiotherapy group than in the non-radiotherapy group; however, the latter was not significantly different (<i>p</i> = 0.0266 and <i>p</i> = 0.064, respectively). After PSM, the SXscores and percentage of high SXscores were significantly higher in the radiotherapy group than in the non-radiotherapy group (22 [interquartile range (IQR) 10.00–30.00] vs. 15.00 [IQR 4.00–26.00], <i>p</i> = 0.0459), (70.07 vs. 44.44%, <i>p</i> = 0.027), respectively. After adjusting for related risk factors and chemotherapy, the OR of radiotherapy for a high SXscore was 3.674 (95% CI 1.094–12.343) by logistic regression analysis. <b><i>Conclusion:</i></b> Thoracic cancer survivors who underwent radiotherapy have higher SXscores and are at a higher risk of developing anatomically severe CAD, independent of chemotherapy.