INTERIM CONTINUATION (for patients unable to tolerate dose intensive chemotherapy): Patients receive etoposide and cyclophosphamide IV on day 1, methotrexate IV on day 8, mercaptopurine PO on days 8-14, teniposide and cytarabine IV on day 15, dexamethasone PO TID on days 22-26, and vinblastine IV on day 22.