THYMOMA - PROGNOSTIC FACTORS AND TREATMENT OUTCOMES

BACKGROUND. The objective of this study was to establish prognostic fa ctors for thymoma and determine the impact of surgery with or without postoperative radiotherapy. METHODS, Seventy patients treated at the U niversity Hospital Dusseldorf during the period 1954-1991 were retrosp ectively studied. AU thymoma patients underwent surgery, 22 received p ostoperative radiotherapy, and 3 also received chemotherapy. According to thymoma staging as described previously by Masaoka et al., 21% wer e Stage I, 26% Stage II, 43% Stage III, 7% Stage TVA, and 3% Stage IVB . Lymphocytic type disease was found in 36% of patients, lymphoepithel ial type in 33%, epithelial type in 23%, and spindle cell type in 9%. The relevance of Karnofsky performance status (KPS), gender, age, myas thenia gravis, histology, tumor size, and stage to survival was determ ined by univariate analysis, and their independent significance was te sted by multivariate analysis. Survival rates were calculated using th e Kaplan-Meier method and the log rank lest. RESULTS. In univariate an alysis, KPS (P < 0.001), histologic type (P = 0.0093), and stage (P = 0.0001) proved to be significant predictors of overall survival. Spind le cell type was associated with the best and epithelial type the wors t prognosis; patients with the latter type had a 5-year survival rate of 30%. Multivariate analysis revealed that stage, histology, and KPS were predictive of overall survival. In Stages III and IV, relapses we re reduced by postoperative radiotherapy from 50% to 20%. The site of relapse was outside the irradiated area in 80% of patients. Disease fr ee survival (P = 0.36) and median survival (P = 0.72) of patients with completely resected advanced thymomas did not differ from that for pa tients with incompletely resected tumors who received radiotherapy. CO NCLUSIONS. Postoperative radiotherapy can improve local control in pat ients with advanced thymoma. Survival after incomplete resection is no t compromised when postoperative radiotherapy is employed. KPS should be considered an important prognostic factor in future studies. Cancer 1998;83:1495-503. (C) 1998 American Cancer Society.