DISEASE CHARACTERISTICS:

• Histologically proven, newly diagnosed, supratentorial malignant glioblastoma multiforme not requiring immediate radiation therapy
• At least 1 bidimensionally measurable lesion

PATIENT CHARACTERISTICS:

Age:

• 18 and over

Performance status:

• Karnofsky 70-100%

Life expectancy:

• Greater than 12 weeks

Hematopoietic:

• Absolute neutrophil count at least 1500/mm^3
• Platelet count at least 100,000/mm^3
• Hemoglobin at least 10 g/dL

Hepatic:

• Bilirubin less than 1.5 times upper limit of normal (ULN)
• SGOT and SGPT less than 2.5 times ULN
• Alkaline phosphatase less than 2 times ULN

Renal:

• BUN less than 1.5 times ULN
• Creatinine less than 1.5 times ULN

Other:

• Must be neurologically stable
• No systemic disease
• No acute infection requiring intravenous antibiotics
• No frequent vomiting
• No other medical condition that would interfere with oral medication intake such as partial bowel obstruction

• No prior or concurrent malignancies except:

  • Surgically cured carcinoma in situ of the cervix
  • Basal or squamous cell carcinoma of the skin
• HIV negative
• No AIDS-related illness
• Not pregnant or nursing
• Fertile patients must use effective contraception

PRIOR CONCURRENT THERAPY:

Biologic therapy:

• No prior biologic therapy
• No concurrent biologic therapy (growth factors or erythropoietin)

Chemotherapy:

• No prior chemotherapy
• No other concurrent chemotherapy

Endocrine therapy:

• Concurrent steroid allowed (must be on stable dose for at least 1 week prior to study)

Radiotherapy:

• No prior radiation therapy
• No prior interstitial brachytherapy
• No prior radiosurgery to the brain
• Not requiring immediate radiation therapy
• No concurrent radiotherapy

Surgery:

• Recovered from any effects of prior surgery
• At least 2 weeks since prior surgical resection

Other:

• No other concurrent investigational drugs