Follow-up study of thymomas with special reference to their clinical stages.

Follow-up data were obtained for 96 cases of thymoma. The one-year survival rate was 84.3%, the three-year 77.1%, the five-year 74.1%, and the ten-year 57.1%. The five-year survival rate of total resection group was 88.9%; that of non-radically treated group was 44.4%. Clinical stages were defined: Stage I--macroscopically encapsulated and microscopically no capsular invasion; Stage II--1. macroscopic invasion into surrounding fatty tissue of mediastinal pleura, or 2. microscopic invasion into capsule; Stage III--macroscopic invasion into neighboring organ; Stage IVa--pleural or pericardial dissemination; Stage IVb--lymphogenous or hematogenous metastasis. Five-year survival rates of each clinical stage were 92.6% in Stage I, 85.7% in Stage II, 69.6% in Stage III, and 50% in Stage IV. Recurrence after total resection was found in six of 69 cases. Seven of 13 patients treated by subtotal resection survived more than five years with postoperative radiotherapy.