Surgery Plus Radiation Therapy With or Without Chemotherapy in Treating Children With Primitive Neuroectodermal Tumors of the CNS

RATIONALE: Drugs used in chemotherapy use different ways to stop tumor cells from dividing so they stop growing or die. Radiation therapy uses high-energy x-rays to damage tumor cells. It is not yet known whether undergoing surgery plus radiation therapy is more effective with or without chemotherapy for primitive neuroectodermal tumors of the CNS. PURPOSE: Randomized phase III trial to compare the effectiveness of surgery plus radiation therapy with or without chemotherapy in treating patients who have primitive neuroectodermal tumors of the CNS.