Regimen A: Patients receive methotrexate IT on day 1* and then PO on days 8, 15, 22, 29, and 36; mercaptopurine PO QD on days 1-42; dexamethasone PO twice daily (BID) on days 1-5; and low-dose vincristine IV and cyclophosphamide IV over 1 hour on days 43, 50, 57, and 64. Treatment repeats every 70 days for 5 courses.