Thymic tumors and results of radiotherapy.

Aim: The aim of this study was to evaluate thymic epithelial tumors (TETs) for treatment outcomes and prognostic factors on survival.

Background: TETs are very rare neoplasms and multidisciplinary approach is recommended according to prognostic factors.

Materials and methods: Between 1995 and 2013, 31 patients were treated with median 5400 cGy (range: 1620-6596 cGy) radiotherapy (RT). Eleven patients received adjuvant or concurrent chemotherapy. There were 25 thymomas, 4 thymic carcinomas and 2 thymic neuroendocrin carcinomas. According to Masaoka, staging and WHO classification, cases were divided to good ( n : 10), moderate ( n : 9) and poor ( n : 12) prognostic risk groups. Survival was calculated from diagnosis.

Results: In January 2016, 22 cases were alive with median 51.5 months (range: 2-170.5) follow-up. Recurrences were observed in 29% of patients in median 29.5 months (range: 6.5-105). Local control, mean overall (OS) and disease-free survival (DFS) rates were 86%, 119 and 116 months, respectively. There was a significant difference for R0 vs. R+ resection (81% vs. 43%, p  = 0.06, and 69% vs. 46%, p  = 0.05), Masaoka stage I-II vs. III-IV (75% vs. 52%, p  = 0.001, and 75% vs. 37%, p  < 0.001), and also prognostic risk groups (100% vs. 89% vs. 48%, p  = 0.003, and 100% vs. 87% vs. 27%, p  = 0.004) in terms of 5-year OS and DFS, respectively.

Conclusion: In our study, prognostic risk stratification was shown to be a significant predictor of survival. There is a need to investigate subgroups that may or may not benefit from adjuvant RT.