RATIONALE: Drugs used in chemotherapy work in different ways to stop the growth of tumor cells, either by killing the cells or by stopping them from dividing. Radiation therapy uses high-energy x-rays to kill tumor cells. Giving more than one drug (combination chemotherapy) with or without radiation therapy may kill more tumor cells.

PURPOSE: This phase III trial is studying how well combination chemotherapy with or without radiation therapy works in treating young patients with newly diagnosed stage III or stage IV Wilms tumor.