Dexamethasone Compared With Prednisone During Induction Therapy and MTX With or Without Leucovorin During Maintenance Therapy in Treating Patients With Newly Diagnosed High-Risk Acute Lymphoblastic Leukemia
RATIONALE: Drugs used in chemotherapy, such as dexamethasone, prednisone, methotrexate, and leucovorin calcium (LCV), work in different ways to stop cancer cells from dividing so they stop growing or die. Giving more than one drug may kill more cancer cells. It is not yet known which combination chemotherapy regimen is more effective in treating acute lymphoblastic leukemia. PURPOSE: This randomized phase III trial is studying dexamethasone to see how well it works compared to prednisone during induction therapy. This trial is also studying methotrexate and leucovorin calcium to see how well they work compared to methotrexate alone during maintenance therapy in treating patients with newly diagnosed acute lymphoblastic leukemia.