Patients receive induction intensification chemotherapy comprising high-dose methotrexate IV over 24 hours; triple intrathecal therapy as per induction therapy on days 22 and 29; and leucovorin calcium IV every 6 hours for 2 doses beginning 42 hours after start of high-dose methotrexate and then orally every 6 hours for 3 doses. Patients also receive etoposide IV over 2 hours and cyclophosphamide IV over 30 minutes on days 36-40. Patients receive G-CSF SC or IV beginning on day 41 and continuing until blood counts recover.