- Regimen A: Patients receive vincristine IV over 1 minute weekly on weeks 6-13, 15-19, 23-27, 29, 32-35, 38-39, and 41; dactinomycin IV over 1 minute weekly on weeks 6, 12, 23, 29, 35, and 41; and cyclophosphamide IV over 30-60 minutes weekly on weeks 6, 12, 16, 19, 23, 29, 35, and 41. Patients also receive irinotecan IV over 1 hour daily, 5 days a week, on weeks 9, 10, 26, 27, 32, 33, 38, and 39 and undergo radiotherapy daily, 5 days a week, on weeks 15-22.