Temozolomide During and After Radiation Therapy in Treating Patients Who Have Undergone Previous Surgery and Placement of Gliadel Wafers for Newly Diagnosed Glioblastoma Multiforme

RATIONALE: Drugs used in chemotherapy, such as temozolomide, 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 temozolomide during and after radiation therapy may kill any tumor cells that remain after surgery and placement of Gliadel wafers. PURPOSE: This phase II trial is studying how well giving temozolomide during and after radiation therapy works in treating patients who have undergone previous surgery and placement of Gliadel wafers for newly diagnosed glioblastoma multiforme.