Inclusion Criteria

DISEASE CHARACTERISTICS:

- Histologically proven supratentorial low-grade (grade II) glioma of any of the
following histologic subtypes:

- Oligodendroglioma

- Astrocytoma

- Oligoastrocytoma

- Has undergone surgical resection or biopsy within 35 days after diagnosis of
low-grade glioma

- Study treatment must begin between 14 days and 4 months after surgical resection
or biopsy

- Evaluable disease by gadolinium-MRI

PATIENT CHARACTERISTICS:

- Karnofsky performance status 60-100%

- Absolute neutrophil count ≥ 1,500/mm^3

- Platelet count ≥ 100,000/mm^3

- Hemoglobin ≥ 10 g/dL

- Creatinine < 1.5 times upper limit of normal (ULN)

- BUN < 1.5 times ULN

- Bilirubin < 1.5 times ULN

- SGOT < 2.5 times ULN

- Alkaline phosphatase < 2 times ULN

- Life expectancy > 12 weeks

- No nonmalignant systemic disease resulting in the patient being a poor medical risk

- No acute infection requiring intravenous antibiotics

- No frequent vomiting or medical condition that would interfere with oral medication
intake (e.g., partial bowel obstruction)

- No other concurrent malignancies except surgically cured carcinoma in situ of the
cervix or basal cell or squamous cell carcinoma of the skin

- Prior malignancies must be in remission for ≥ 5 years

- No known HIV positivity

- No AIDS-related illness

- Not pregnant or nursing

- Negative pregnancy test

- Fertile patients must use effective contraception

PRIOR CONCURRENT THERAPY:

- See Disease Characteristics

- No prior radiotherapy, interstitial brachytherapy, or radiosurgery for low-grade
glioma

- No prior biological therapy or chemotherapy for low-grade glioma

- No other concurrent chemotherapy

- No concurrent radiotherapy or biological therapy

- No concurrent prophylactic growth factors

- No concurrent epoetin alfa

- No other concurrent investigational drugs