Analysis of surgical strategy of treating thymomas: A single center experience.

Abstract

e18519 Background: Thymomas are epithelial thymic tumors, generally considered to have an indolent growth pattern but are malignant. 20-40% of patients with thymomas have paraneoplastic syndromes,including myasthenia gravis(MG). The objective of this study is to evaluate outcome of surgical treatment to thymoma and determine whether the different pathological and clinical characteristics of thymomas influences the prognosis in thymoma patients. Methods: We retrospectively studied data from 228 consecutive patients operated on from1992 to 2007. All thymic epithelial tumors were reclassified according to the WHO histologic classification, and the Masaoka clinical staging system. Patients with type A and stage I thymoma had no adjuvant therapy. Most patients with types AB and B1 thymomas had radiotherapy postoperatively. Patients (stageII, III) were treated with adjuvant mediastinal radiation therapy, and both adjuvant radiation therapy and chemotherapy was administered to stage IV and type C one month after operation. For patients with tumor nodules found on the pleural surface, cytoreductive surgery was performed. After that, patients had both adjuvant radiation therapy and chemotherapy. Results: There were no peri-operative deaths. 19 cases were inoperable. 16.2% patients had postoperative complications: The proportions of type A, AB, B1, B2, B3, and C thymoma in this data were 0%, 22.4%, 26.4%, 30.4%, 20.8%, and 0% respectively in patients with MG. Microthymoma was identified in the paraneoplastic thymus of 3 patients. There were 198 patients followed up. There was no recurrence in patients with type A and a few patients with type AB, B1, B2, B3 and C recurred. The actuarial 5- and 10-year survival rates were 89.6% and 80.5% respectively. Within 5 years postoperatively, 6 of 16 deaths died of myasthenia crisis, 6 were attributable to inoperable tumors (stageIV) and type C thymoma. Conclusions: Surgical treatment to thymoma has a sound prognosis. Multimodality treatment of stage III or IV thymomas may be critical to improve the 5-year survival rate. MG seldom occurs in type A and C thymoma. The main cause of death is myasthenia crisis for thymoma patients with MG and stage IV and /or type C for thymoma patients without MG.