Supplementary Material for: Clinical features, treatment modalities and outcomes of elderly thymoma patients: A propensity–matched study based on the SEER database

Introduction: Thymoma is a common mediastinal tumor, but few studies have been performed in thymoma patients 80 years or older. This study aimed to analyze the clinical features, treatment modalities and survival outcomes of thymoma patients at least 80 years old and compare these features to those of patients younger than 80 years old. Method: Data from thymoma patients in the Surveillance, Epidemiology and End Results database between 2000 and 2019 were selected. Clinical features, treatment modalities of the two age groups were compared. Survival rates were calculated by the Kaplan-Meier method and the log-rank test was used to compare survival rates between two groups. Propensity score matching was used based on whether surgery was performed. Univariate and multivariate Cox proportional–hazards regression analyses were performed to identify independent prognostic factors. Results: Compared with the younger patients, the patients aged 80 years or older had a similar distribution of Masaoka–Koga tumor stage, a higher proportion of type A thymoma, and a lower recurrence rate in the early stage. In elderly patients after propensity score matching, the overall survival and cancer–specific survival were better in the surgery group with complete resection and similar benefit from surgery as younger patients were observed. Conclusion: In thymoma patients aged 80 years or older, surgery still plays an important role in survival outcome. Compared with younger patients, older patients had unique clinical features.