Phase III Trial of Anaplastic Glioma Without 1p/19q Loss of Heterozygosity (LOH)

DISEASE CHARACTERISTICS: * Histologically confirmed diagnosis of 1 of the following: * Anaplastic oligodendroglioma * Anaplastic oligoastrocytoma * Anaplastic astrocytoma * Newly diagnosed disease * Prior surgery for a low grade tumor is allowed, provided histological confirmation of an anaplastic tumor is present at the time of progression * Absence of combined 1p/19q loss * Tumor material available for central 1p/19q assessment, central O6-methylguanine-DNA methyltransferase promoter methylation status assessment, isocitrate dehydrogenase mutation analysis, and central pathology review * Patients must be on a stable or decreasing dose of steroids for at least two weeks prior to randomization PATIENT CHARACTERISTICS: * WHO performance status 0-2 * Absolute Neutrophil Count (ANC) ≥ 1.5 x 10\^9 cells/L * Platelet count ≥ 100 x 10\^9 cells/L * Bilirubin \< 1.5 x upper limit of normal (ULN) * Alkaline phosphatase \< 2.5 x ULN * Aspartate Aminotransferase (AST) and Alanine Aminotransferase (ALT) \< 2.5 x ULN * Serum creatinine \< 1.5 x ULN * Not pregnant or nursing * Fertile patients must use effective contraception * No known HIV infection or chronic hepatitis B or hepatitis C infection * No other serious medical condition that would interfere with follow-up * No medical condition that could interfere with oral medication intake (e.g., frequent vomiting or partial bowel obstruction) * No other prior malignancies except for any malignancy which was treated with curative intent more than 5 years prior to registration and adequately controlled limited basal cell carcinoma of the skin, squamous cell carcinoma of the skin, or carcinoma in situ of the cervix * No prior or concurrent malignancies at other sites except for surgically cured carcinoma in situ of the cervix or nonmelanoma skin cancer * No psychological, familial, sociological, or geographical condition that would potentially hamper compliance with the study protocol and follow-up schedule PRIOR CONCURRENT THERAPY: * See Disease Characteristics * No prior chemotherapy, including carmustine-containing wafers (Gliadel®) * No prior radiotherapy to the brain * No concurrent growth factors unless vital for the patient * No other concurrent investigational treatment * No other concurrent anticancer agents