RATIONALE: Drugs used in chemotherapy, such as vincristine, dactinomycin, and doxorubicin, 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 these treatments after surgery may kill any tumor cells that remain after surgery. Sometimes, after surgery, the tumor may not need additional treatment until it progresses. In this case, observation may be sufficient.

PURPOSE: This phase III trial is studying vincristine, dactinomycin, and doxorubicin with or without radiation therapy or observation only to see how well they work in treating patients undergoing surgery for newly diagnosed stage I, stage II, or stage III Wilms tumor.