Background: This study aimed to determine the role of postoperative adjuvant therapy in patients with thymic carcinoma following complete resection.

Methods: We conducted a retrospective analysis of patients with stage I-III or N1+ thymic carcinomas who underwent complete resection at our center between 2006 and 2020. Data on the clinical characteristics and postoperative adjuvant therapies were collected.

Results: One hundred and twenty patients were enrolled. Five (4.2%) patients received only postoperative chemotherapy, 36 (33.0%) received only postoperative radiotherapy, 75 (62.5%) received postoperative chemoradiotherapy, and four (3.3%) did not receive any postoperative therapy. During a median follow-up period of 65 months, disease failure was observed in 46 (38.3%) patients, and 28 (23.3%) patients died. The 5‑year disease-free survival (DFS) and overall survival (OS) rates were 58.7 and 81.4%, respectively. Patients who underwent different postoperative therapies exhibited varying prognoses. Radiotherapy reduced the risks of failure (p < 0.001) and death (p < 0.001), whereas chemotherapy did not (p = 0.198 and 0.260 respectively). Subgroup analyses revealed that stage III/IV patients who received chemotherapy had a lower relapse risk (p = 0.045) and improved OS (p = 0.064). Multivariate analysis demonstrated that radiotherapy alone (hazard ratio [HR], 0.24; p = 0.023) independently predicted OS.

Conclusions: Adjuvant radiotherapy should be recommended for patients with thymic carcinoma who have undergone complete resection. Further exploration is needed to clarify the role of adjuvant chemotherapy.