ENTIRE HEMITHORAX IRRADIATION FOLLOWING COMPLETE RESECTION IN PATIENTS WITH STAGE II-III INVASIVE THYMOMA

Purpose: To evaluate the feasibility and efficacy of prophylactic enti re hemithorax irradiation (EH) in addition to mediastinal irradiation (MRT) following a complete resection in Stage II-III invasive thymoma. Methods and Materials: Forty-three patients with invasive thymoma tre ated with surgery and radiation therapy between 1978 and 1993 were ana lyzed retrospectively. All 43 patients underwent a complete surgical r esection and were judged to have Masaoka's Stage II-III invasive thymo ma, Of these, 23 patients received EH and MRT (EH-MRT) and the remaini ng 20 received MRT, Of the 23 patients with EH-MRT, 11 were Stage II a nd 12 Stage III. Of the 20 with MRT, 11 were Stage II and 9 Stage III, In most cases, EH was 15 Gy per 15 fractions over 3 weeks (without lu ng compensation calculation), In both the EH-MRT and MRT group, the to tal radiation doses to the mediastinum were similar with a median of 4 0 Gy, The median follow-up time after surgery was 63 months and no pat ients were lost to follow-up. Results: Only one of the 23 patients wit h EH-MRT relapsed, On the other hand, eight of the 20 with MRT relapse d, six of whom died of disease, The pleura was the most common site of failure, At 5 years, the relapse-free rate was 100% for those receivi ng EH-MRT and 66% for those with MRT(p = 0.03); the overall survival r ate was 96% for those with EH-MRT, and 74% for those with MRT (p: not significant), The only significant treatment-related complication was radiation pneumonitis requiring treatment, in one patient who received MRT and three who received EH-MRT, including one death of a 72-year-o ld man and one 68-year-old woman with severe lung fibrosis. Conclusion : Except for elderly patients, EH-MRT following a macroscopically comp lete resection appears to be safe and feasible, and can reduce intrath oracic relapses.