Risk of cardiac‐related mortality in stage IIIA‐N2 non‐small cell lung cancer: Analysis of the Surveillance, Epidemiology, and End Results (SEER) database

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.