Radiation Therapy Combined With Chemotherapy in Treating Patients With Anaplastic Astrocytoma or Mixed Gliomas

RATIONALE: Radiation therapy uses high-energy x-rays to damage tumor cells. Drugs used in chemotherapy, such as temozolomide, carmustine, and lomustine, use different ways to stop tumor cells from dividing so they stop growing or die. Combining radiation therapy with chemotherapy may kill more tumor cells. PURPOSE: This randomized phase III trial is studying radiation therapy and temozolomide to see how well they work compared to radiation therapy and carmustine or lomustine in treating patients with anaplastic astrocytoma or mixed gliomas.