OUTLINE: Patients receive the first course of chemotherapy as soon as possible after diagnosis and staging. Methotrexate (MTX) IV is administered over 40-60 minutes on days 1 and 15. Cytarabine (AraC) is administered intrathecally on days 1 and 15. The second course of chemotherapy begins on day 29 or after bone marrow recovery. Radiation therapy begins no later than 3 weeks after completing chemotherapy. Patients are followed until death.