Postoperative radiotherapy improves overall survival and was not associated with a statistically significant increase in cardiac-specific mortality in thymoma patients: a propensity score-matched analysis of the SEER database.

Background: Thymoma is an uncommon cancer of the thymus and postoperative radiotherapy (PORT) is often considered for selected patients with high-risk or locally advanced thymoma after resection. The effect of PORT on overall survival (OS) and cardiac-specific mortality in patients with thymoma is not well understood. The purpose of this study was to assess the impact of PORT on OS and cardiac-specific mortality in resected thymoma patients. Methods: We analyzed the data from Surveillance, Epidemiology, and End Results (SEER) database to identify patients with thymoma who had a cancer-directed operation alone or with PORT. A propensity score matching (PSM) was employed to adjust for imbalances in two groups. OS was analysed with Kaplan-Meier. Comparison of cumulative incidence curves for cardiac-specific mortality between the groups was performed using Fine and Gray's model. Results: There was a total of 3,434 patients with thymoma. After 1:1 matching, 1,078 patients remained in each group and PORT was independently correlated with better survival (P=0.004). The 5-year OS was 88.2% for the PORT group and 84.1% for the non-PORT group. With respect to cardiac-specific mortality, the cumulative incidence at 15 years for PORT Conclusions: PORT was associated with improved long-term survival. No statistically significant increase in cardiac-specific mortality was observed; however, a moderate increase in risk cannot be excluded given the limited number of cardiac events. These findings suggest that PORT remains an appropriate part of thymoma management.