PROGNOSTIC FACTORS AND LONG-TERM RESULTS AFTER THYMOMA RESECTION - A SERIES OF 307 PATIENTS

Three hundred seven cases of patients who underwent operation for thym oma (196 of whom had myasthenia gravis) were analyzed to assess the pr ognostic values of Masaoka clinical staging, completeness of resection , histologic classification, history of myasthenia gravis, and postope rative radiotherapy. According to the Masaoka staging system, 135 thym omas were stage I, 70 were stage II, 83 were stage III, and 19 were st age IV. According to the Verley and Hollmann histologic classification system, 67 thymomas were type 1, 77 were type 2, 139 were type 3, and 24 were type 1. Two hundred sixty patients underwent complete resecti on, 30 underwent incomplete resection, and 17 underwent biopsy. Postop erative radiotherapy was performed mainly in cases of invasive or meta static thymoma. Mean follow-up was 8 years; eight patients were unavai lable for fellow-up. The overall 10- and 15-year survivals were 67% an d 57%, respectively. In univariate analysis, three prognostic factors were established: completeness of resection, Masaoka clinical staging, and histologic classification. Furthermore, among patients with stage III thymomas, survival was significantly higher for patients with com plete resection than for patients with incomplete resection (p < 0.001 ). Completeness of resection should therefore be taken into account In clinical-pathologic staging. We did not find any significant differen ce with respect to disease-free survival between patients who had post operative radiotherapy and those who did not. In multivariate analysis , the sole significant prognostic factor was completeness of resection . On the basis of these findings, a new clinical-pathologic staging sy stem is proposed.