Abstract
BACKGROUND: In this study, we aimed to investigate the association between postoperative radiotherapy (PORT) and cardiac-related mortality in patients with stage IIIA-N2 non-small cell lung cancer (NSCLC) using the Surveillance, Epidemiology, and End Results (SEER) database. METHODS: The United States (US) population based on the SEER database was searched for cardiac-related mortality among patients with stage IIIA-N2 NSCLC. Cardiac-related mortality was compared between the PORT and Non-PORT groups. Accounting for mortality from other causes, Fine and Gray's test compared cumulative incidences of cardiac-related mortality between both groups. Univariate and multivariate analysis were performed using the competing risk model. RESULTS: From 1988 to 2016, 7290 patients met the inclusion criteria: 3386 patients were treated with PORT and 3904 patients with Non-PORT. The five-year overall incidence of cardiac-related mortality was 3.01% in the PORT group and 3.26% in the Non-PORT group. Older age, male sex, squamous cell lung cancer, earlier year of diagnosis and earlier T stage were independent adverse factors for cardiac-related mortality. However, PORT use was not associated with an increase in the hazard for cardiac-related mortality (subdistribution hazard ratio [SHR] = 0.99, 95% confidence interval [CI]: 0.78-1.24, p = 0.91). When evaluating cardiac-related mortality in each time period, the overall incidence of cardiac-related mortality was decreased over time. There were no statistically significant differences based on PORT use in all time periods. CONCLUSIONS: With a median follow-up of 25 months, no significant differences were found in cardiac-related mortality between the PORT and Non-PORT groups in stage IIIA-N2 NSCLC patients.