OUTLINE: This is a randomized, multicenter study. Patients are stratified by center. All patients receive cyclophosphamide, doxorubicin, and vincristine by IV bolus alternating with 3 days of daily etoposide IV infusion over 60-120 minutes and cisplatin IV infusion over 30 minutes. This treatment alternates every 3 weeks for six courses. Patients are randomized to have thoracic radiotherapy either with course 2 (arm I) or with course 6 (arm II) of chemotherapy. Patients in arm I are given 1 week of rest between radiotherapy and the second course of chemotherapy. If there is no disease progression after chemotherapy and locoregional irradiation, and a repeat brain scan is negative, patients receive prophylactic brain irradiation. Patients are followed monthly for the first year and then every 2 months thereafter.