- Standard therapy: Patients receive vincristine IV over 1 minute weekly on weeks 0-13, 15-19, 23-27, 29, 32-35, 38, and 41; dactinomycin IV over 1 minute weekly on weeks 0, 6, 9, 12, 23, 26, 29, 32, 35, 38, and 41; and cyclophosphamide IV over 30-60 minutes weekly on weeks 0, 3, 6, 9, 12, 16, 19, 23, 26, 29, 32, 35, 38, and 41. Patients without evidence of intracranial extension receive radiotherapy once daily, 5 days a week, during weeks 15-22. Patients with evidence of intracranial extension, or who require emergency radiotherapy, receive radiotherapy during weeks 0-6. Dactinomycin is withheld during radiotherapy.