Prognostic Factor of Completely Resected and Pathologic T3 N0 M0 Thymic Epithelial Tumor

Background: A multiinstitutional study was conducted to analyze prognosticators of completely resected and pathologic T3 N0 M0 (pT3 N0 M0) stage thymic epithelial tumors. Methods: A total of 607 patients with surgically treated thymic epithelial tumors between June 1988 and December 2017 were enrolled. A Cox proportional hazards model and an inverse probability of treatment weighting–adjusted analysis using the propensity score were performed. Results: A total of 394 patients with thymoma and 130 patients with thymic carcinoma underwent complete tumor resections. Forty-one thymomas and 49 thymic carcinomas were confirmed as pT3 N0 M0 stage tumors. Postoperative adjuvant radiotherapy was associated with improved disease-free and overall survival in patients with thymoma (hazard ratio [HR], 0.40; 95% confidence interval [CI], 0.23 to 0.69; and HR, 0.24; 95% CI, 0.11 to 0.52, respectively) and in patients with thymic carcinoma (HR, 0.15; 95% CI, 0.07 to 0.33; and HR, 0.12; 95% CI, 0.05 to 0.31, respectively). Although lung invasion was associated with poor disease-free survival (HR, 3.28; 95% CI, 1.90 to 5.89) and overall survival (HR, 2.60; 95% CI, 1.21 to 6.07), male sex (HR, 1.88; 95% CI, 1.10 to 3.18), older age (HR, 2.77; 95% CI, 1.29 to 5.70), and advanced histologic features (HR, 3.84; 95% CI, 1.42 to 14.51) were associated with poor overall survival in patients with pT3 N0 M0 thymoma. Adjuvant chemotherapy was associated with improved disease-free survival (HR, 0.11; 95% CI, 0.03 to 0.41) and overall survival (HR, 0.11; 95% CI, 0.06 to 0.20) in patients with pT3 N0 M0 thymic carcinoma with superior vena cava or innominate vein invasion. Conclusions: Postoperative radiotherapy was associated with improved survival in patients with pT3 N0 M0 thymic epithelial tumors. Lung invasion was associated with poor survival in patients with pT3 N0 M0 thymoma. Adjuvant chemotherapy was associated with improved survival in patients with pT3 N0 M0 thymic carcinoma with superior vena cava or innominate vein invasion.