OUTLINE: This is a randomized, multicenter study. Patients without CNS disease at diagnosis, achieving a specified early marrow response profile and M1 marrow status of less than 5% blasts in the bone marrow (regardless of the proportion of mature lymphocytes) by day 28 of induction therapy, and remaining event free with favorable bone marrow status and cytogenetics between day 21 and 28 of consolidation therapy are randomized to one of four treatment arms. Patients with CNS disease at diagnosis are assigned to treatment arm II and undergo cranial irradiation. Patients with any of the following unfavorable bone marrow features and/or unfavorable cytogenetic features are assigned to the augmented treatment regimen by day 21 of induction chemotherapy or at the beginning of consolidation chemotherapy: