This randomized phase III trial is studying maintenance chemotherapy to see how well it works compared to observation following induction chemotherapy and radiation therapy in treating young patients with newly diagnosed ependymoma. Drugs used in chemotherapy, such as vincristine sulfate, carboplatin, cyclophosphamide, etoposide, and cisplatin, work in different ways to stop the growth of tumor cells, either by killing the cells or by stopping them from dividing. Giving more than one drug (combination chemotherapy) may kill more tumor cells. Radiation therapy uses high-energy x-rays to kill tumor cells. Specialized radiation therapy that delivers a high dose of radiation directly to the tumor may kill more tumor cells and cause less damage to normal tissue. Giving chemotherapy with radiation therapy may kill more tumor cells and allow doctors to save the part of the body where the cancer started.