Thymic tumors: radiotherapy experience for single institute.

Purpose: The aim is to evaluate treatment outcomes and prognostic factors in patients with thymic epithelial tumor (TET) treated with radiotherapy (RT).

Methods: Sixty-four patients were treated between 2000 and 2023. The median age was 52 years (20-83), and 81% of underwent R0 resection. The stage (s) distribution for I, II, III, and IV were 5%, 61%, 26%, and 8% by Masaoka-Koga and 63%, 11%, 17%, and 9% by TNM, respectively. WHO types A/AB/B/C and thymic neuroendocrine tumors were seen in 5%, 22%, 64%, 6%, and 3% of patients, respectively. The median RT dose was 5040 cGy (1620-6596). Survival was calculated from the beginning of RT.

Results: The median follow-up was 70 months (1.5-268). The median time to recurrence was 30 months (6.5-106), seen in 23% of patients. Mean overall (OS), progression-free survival (PFS) and 5‑year local control were 141, 138 months, and 82.4%, respectively. In univariate analysis, the presence of organ invasion and TNM stage were significant as new prognostic factors for survival (p < 0.05). In multivariate analysis, the high-risk group (B2/B3/C) and another surgical center (p < 0.05) for OS, and KPS ≤ 80, thymic carcinoma, and Masaoka-Koga sIII-IV (p < 0.05) for PFS were identified as unfavorable prognostic factors.

Conclusion: Recurrence in TET can occur over a longer period. In this study, 5‑year local control of 82.4% was achieved. The prognostic importance of KPS, histology, Masaoka-Koga stage, risk group, and surgical center was demonstrated. Advances in the diagnosis, staging, and treatment of TET will enable more personalized treatment.