Tumor size exceeding 5 cm as a valid prognostic factor in all stages of thymic epithelial tumors.

PURPOSE: This study investigated the prognostic factors of thymic epithelial tumors (TETs) to identify patients who require multidisciplinary treatment and improve the TET prognosis. METHODS: We retrospectively reviewed the data of 268 TET patients. Prognostic variables for the overall survival (OS) were analyzed in all TET stages (n = 268), and the recurrence-free survival (RFS) was analyzed in patients who achieved complete resection (n = 164). RESULTS: The median follow-up period was 7 years; thymic carcinomas (TCs) and advanced stages of tumor, node, and metastasis (TNM) classification had the worse prognosis according to a Kaplan-Meier analysis. The cut-off value of the tumor size to predict the OS and RFS was determined using modified Harrell's c-index calculated by a Cox regression analysis of the OS. Regarding the OS, a multivariate analysis revealed that age > 70 years old (p = 0.011), tumor size > 5 cm (p < 0.001), and TCs (p = 0.002) were significant prognostic factors aside from the TNM stage (p < 0.001). Regarding the RFS, tumor size > 5 cm was the only significant prognostic factor in the multivariate analysis (p = 0.002) aside from the TNM stage (p = 0.008). CONCLUSIONS: Tumor size > 5 cm was shown to be a prognostic predictor in addition to the WHO and TNM classifications. Therefore, multidisciplinary treatment should be developed for TET patients with poor prognostic factors, specifically tumor size.