Methods: A total of 203 patients (105 males, 98 females; median age: 49 years; range, 17 to 77 years) with Masaoka-Koga Stage II-IV thymoma between January 2002 and December 2018 were retrospectively analyzed. Data including diagnosis of myasthenia gravis, diagnosis of diabetes mellitus, disease stage, histological type of tumor, capsule invasion and surgical margin status, lymphadenectomy, adjuvant radiotherapy or chemotherapy, time from surgery to the first day of adjuvant treatment, length of hospital stay, and overall and disease-free survival rates were recorded.

Results: Of the patients, 91 had Stage II, 67 had Stage III, and 45 had Stage IV disease. A total of 123 patients (61%) had myasthenia gravis. Seventy-six patients received adjuvant radiotherapy and 48 patients received either neoadjuvant (n=35) or adjuvant (n=25) chemotherapy. Higher disease stage, presence of R1 resection, and treatment with chemotherapy were significant factors for decreased disease-free survival time. Older age, higher disease stage, longer postoperative hospital stay, chemotherapy, and disease recurrence were effective contributors to decreased overall survival time. Adjuvant radiotherapy had a statistically significant positive effect on overall survival only in patients with completely resected Stage IV disease (five-year overall survival: 94.7% vs. 79.1%, respectively; p=0.015). In the multivariate analysis, older age (hazard ratio: 4.26), higher disease stage (hazard ratio: 2.95), and longer hospitalization time (hazard ratio: 3.81) were significant prognostic factors for overall survival. Patients with local recurrence who underwent complete resection had a survival time comparable to non-recurrent patients (p=0.753).

Conclusion: For patients with thymoma, higher disease stage, age ?50 years, longer hospitalization, and need for chemotherapy are associated with worse survival rates. Adjuvant chemotherapy has a positive impact on Stage IV disease. Resection of recurrent lesions has a valuable impact on survival.