Arm I: Patients receive vincristine IV over 5-10 minutes once a week on weeks 0-12, 15, 18-24, 27, 30-36, and 39. Dactinomycin IV is administered over 15-20 minutes once a week on weeks 0, 3, 6, 9, 12, 21, 24, 27, 30, 33, 36, and 39. Cyclophosphamide IV is administered over 30-60 minutes once a week on weeks 0, 3, 6, 9, 12, 15, 18, 21, 24, 27, 30, 33, 36, and 39. After the initial 12 weeks of chemotherapy, depending on tumor shrinkage, patients may undergo surgery. After recovery from surgery, patients receive radiotherapy once a day, 5 days a week, during weeks 12-18. For patients receiving radiotherapy during weeks 0-6, dactinomycin is omitted during weeks 3 and 6 and administered during weeks 15 and 18. For patients receiving radiotherapy during weeks 12-18, dactinomycin is omitted during weeks 15 and 18. Patients showing an adequate response at week 24 continue chemotherapy during weeks 24-39.