OUTLINE: This is a randomized study. Patients are stratified according to tumor subtype (astrocytoma [mixed-astro dominant or equal astro/oligo mix] vs oligodendroglioma [mixed-oligo dominant]), age (younger than 40 vs at least 40), Karnofsky performance status (60-80% vs 90-100%), and contrast enhancement on preoperative scan (present vs absent). Patients with low-risk disease (younger than 40 years old whose tumors have been surgically removed) are assigned to arm I. Patients with high-risk disease (at least 40 years old or who have had incomplete tumor removal) are randomized to arm II or III.