OUTLINE: Patients with CNS disease at diagnosis receive craniospinal irradiation on Regimen A at the conclusion of Maintenance chemotherapy. The following acronyms are used: ARA-C Cytarabine, NSC-63878 CF Leucovorin calcium, NSC-3590 CTX Cyclophosphamide, NSC-26271 DNR Daunorubicin, NSC-82151 DOX Doxorubicin, NSC-123127 G-CSF Granulocyte Colony-Stimulating Factor (Amgen), NSC-614629 MTX Methotrexate, NSC-740 PEG-ASP Pegaspargase, NSC-624239 PRED Prednisone, NSC-10023 TG Thioguanine, NSC-752 VCR Vincristine, NSC-67574 VP-16 Etoposide, NSC-141540 Induction: 5-Drug Combination Systemic Chemotherapy with Hematopoietic Stimulation plus 2-Drug Combination Intrathecal Chemotherapy. VCR/PRED/CTX/DNR/PEG-ASP; with G-CSF; plus IT ARA-C/IT MTX. Consolidation: 7-Drug Combination Systemic Chemotherapy with Hematopoietic Stimulation plus Single-Agent Intrathecal Chemotherapy. VCR/PRED/PEG-ASP/VP-16/TG/ARA-C/MTX/CF; with G-CSF; plus IT MTX. Maintenance: Sequential Pulses of 2-, 3-, 3-, and 2-Drug Systemic Chemotherapy Combinations plus Single-Agent Intrathecal Chemotherapy. CTX/TG/IT MTX; VCR/PRED/DOX; VCR/MTX/CF/PEG-ASP; ARA-C/VP-16. Regimen A: Radiotherapy. Craniospinal irradiation using megavoltage equipment.