DISEASE CHARACTERISTICS:

• Histologically confirmed newly diagnosed glioblastoma multiforme or anaplastic astrocytoma

  • Residual tumor on postoperative MRI
• Bidimensionally measurable disease

PATIENT CHARACTERISTICS:

Age:

• Under 65

Performance status:

• Karnofsky or Lansky 70-100% OR
• ECOG 0-2

Life expectancy:

• Not specified

Hematopoietic:

• Absolute neutrophil count at least 1,000/mm^3
• Hemoglobin at least 8 g/dL (transfusion allowed)
• Platelet count greater than 100,000/mm^3

Hepatic:

• Bilirubin less than 1.5 times upper limit of normal (ULN)
• SGPT no greater than 3 times ULN

Renal:

• Age 5 years and under: Creatinine less than 1.2 mg/dL
• Age over 5 to 10 years: Creatinine less than 1.5 mg/dL
• Age over 10 to 15 years: Creatinine less than 1.8 mg/dL
• Age over 15 years: Creatinine less than 2.4 mg/dL

Cardiovascular:

• No myocardial infarction within the past 6 months

Other:

• No other concurrent serious medical condition that would preclude study
• Able to tolerate oral medications
• No prior malignancy for which patient received prior chemotherapy or spinal irradiation
• No history of severe allergic reaction to platinum-containing compounds
• Not pregnant or nursing
• Negative pregnancy test
• Fertile patients must use effective contraception

PRIOR CONCURRENT THERAPY:

Biologic therapy:

• At least 72 hours since prior filgrastim (G-CSF)

Chemotherapy:

• No prior chemotherapy
• No other concurrent chemotherapy

Endocrine therapy:

• Concurrent steroids for tumor-related cerebral edema allowed
• No concurrent corticosteroids for solely antiemetic purposes

Radiotherapy:

• No prior or concurrent radiotherapy

Surgery:

• Recovered from prior surgery
• No concurrent surgery