REGIMEN I (subset 1 patients) [closed to accrual as of 08/13/2010: Patients receive VAC chemotherapy comprising vincristine IV over 1 minute on day 1 of weeks 1-9 and dactinomycin IV over 1 minute and cyclophosphamide IV over 1 hour on day 1 of weeks 1, 4, 7, and 10; VA chemotherapy comprising vincristine IV over 1 minute on day 1 of weeks 13-21 and dactinomycin* IV over 1 minute on day 1 of weeks 13, 16, 19, and 22; and radiotherapy**, 5 days a week, beginning on week 13 and continuing for 4-7 weeks, depending on prescribed dose.