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

This study investigated the prognostic factors of thymic epithelial tumors (TETs) to identify patients who require multidisciplinary treatment and improve the TET prognosis.

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).

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).

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.