Surgical outcomes and reevaluation of treatment strategies for thymomas

Improved histological typing systems for thymic tumors and advances in induction and adjuvant therapy have created the need to reevaluate strategies for the management of thymoma. We retrospectively studied 73 patients with completely resected thymomas unassociated with myasthenia gravis. The World Health Organization (WHO) histologic classification, clinicopathological features and surgical outcomes were analyzed. Overall survival was 66.2% at 10 years, and the median survival time was 169 months. According to the Masaoka staging system, overall survival rates at 10 years were 94.7% in stage I, 76.1% in stage II, 30% in stage III and 0% in stage IV. In the WHO classification, overall survival rates at 10 years were 91.9% in types A and AB, 50.9% in type B2 and not achieved in type B3. The disease-free interval was slightly shorter in patients with B2 and B3 disease than in those with type A, AB and B1 disease. Advanced thymomas were significantly associated with type B2 and B3 (p<0.01). In stage III and IV disease, adjuvant or neoadjuvant therapy was associated with better survival as compared to no adjuvant therapy (p=0.07). On multivariate analysis, Masaoka stage III and IV disease and extended thymectomy indicated significant, negative and independent risk factors for survival (p<0.01). Masaoka stage I and II thymomas or WHO type A and AB thymomas have favorable prognoses and do not require postoperative adjuvant therapy. Patients with stage III and IV thymomas require additional therapy after surgery.