Prognostic factors of stage I thymic epithelial tumors

Objective According to the tumor-node-metastasis classification for thymic malignancies, the proportion of patients diagnosed with stage I is expected to increase significantly. However, whether those patients have homogenous clinicopathological features and survival has not been fully evaluated. Methods We reviewed 153 consecutive patients with stage I thymic epithelial tumors (133 thymomas, 15 thymic carcinomas, and 5 neuroendocrine tumors) who underwent complete resection at our institution between 2001 and 2016 and evaluated the prognostic significance of their clinicopathological factors. Results The stage I patients accounted for 78% of all thymic epithelial tumors. The 5-year overall survival and recurrence-free survival rates of the 153 patients were 94% and 80%, respectively. The patients with the histology of thymic carcinoma or neuroendocrine tumor and with a tumor larger than 5.0 cm showed significantly worse recurrence-free survival in multivariate analysis ( p = 0.027 and 0.038, respectively). Only the tumor size was revealed as a significant prognostic factor for recurrence-free survival when limited in the 133 cases of thymoma ( p = 0.048). Conclusions Patients with large tumors showed significantly worse recurrence-free survival than those with small tumors both in stage I thymic epithelial tumors and thymomas.