RATIONALE: Drugs used in chemotherapy work in different ways to stop the growth of cancer cells, either by killing the cells or by stopping them from dividing. Giving more than one drug (combination chemotherapy), giving the drugs in different doses, and giving the drugs in different combinations may kill more cancer cells.

PURPOSE: This partially randomized phase III clinical trial is studying different combinations of risk-adapted chemotherapy regimens and their side effects and comparing how well they work in treating younger patients with newly diagnosed standard-risk acute lymphoblastic leukemia.