Dexamethasone Compared With Prednisone During Induction Therapy and Methotrexate With or Without Leucovorin During Maintenance Therapy in Treating Patients With Newly Diagnosed High-Risk Acute Lymphoblastic Leukemia

Inclusion Criteria: * Must be eligible for and enrolled on classification study COG-AALL03B1 * Newly diagnosed B-precursor acute lymphoblastic leukemia * WBC \> 50,000/mm\^3 for patients age 1 to 9 * Any WBC for patients age 10 to 30 OR patients who have received prior steroid therapy OR patients with testicular disease * Whit blood cell (WBC) criteria: * Age 1 - 9 years: WBC \>= 50,000/uL * Age 10 - 30 years: any WBC * Prior steroid therapy: any WBC * Testicular disease: any WBC * Patients shall have had no other prior cytotoxic chemotherapy with the exception of steroids and intrathecal cytarabine * Patients receiving prior steroid therapy (as described in AALL03B1) are eligible for study; the dose and duration of previous steroid therapy should be carefully documented * All patients and/or their parents or legal guardians must sign a written informed consent * All institutional, Food and Drug Administration (FDA), and National Cancer Institute (NCI) requirements for human studies must be met Exclusion Criteria: * Patients with Down syndrome are ineligible to enroll onto this study