Stage III thymic epithelial neoplasms are not homogeneous with regard to clinical, pathological, and prognostic features

Introduction: The main therapeutic approach to a Masaoka stage III thymic epithelial neoplasm (TEN) is surgical resection, and the 5-year survival rate is approximately 60%. According to the Masaoka staging system, invasion of neighboring organs is classified as stage III disease, regardless of the number of organs involved or the size of the tumor. We retrospectively analyzed the prognostic significance associated with the extent of disease in patients with Masaoka stage III TENs. Methods: From 1995 to 2006, 241 patients were identified with thymomas. Among these patients, 59 were diagnosed with Masaoka stage III disease. The patients with a stage III TEN were advised to have extended thymectomy with en bloc resection of the invaded structures as the initial treatment. The prognostic significance of the size, organs invaded, and other factors were analyzed. Results: The overall survival rates for the stage III patients were 83% and 64%, and the recurrence-free survival rates were 56% and 51%, at 5 and 8 years, respectively. Patients with a low-grade World Health Organization classification (p = 0.0202) or a complete resection (p < 0.0001) had a better overall survival. In addition, patients with tumors less than 6.5 cm (p = 0.0311) or with pericardium invasion (p = 0.0299) had a better recurrence-free survival. The patients with limited disease had a better prognosis for a recurrence-free survival than did patients with extensive disease (p = 0.0007). CONCLUSIONS:: Heterogeneous prognostic subgroups based on tumor size and organs invaded were identified in patients with Masaoka stage III TENs. Therapeutic plans, based on these subgroups, will potentially improve patient management and treatment outcomes.