DISEASE CHARACTERISTICS:

• Histologically confirmed glioblastoma multiforme with areas of necrosis

  • Tumor must be supratentorial
• Diagnosis made by surgical biopsy or excision
• No recurrent or multifocal disease
• No metastases detected below the tentorium or beyond the cranial vault
• Tumor tissue and serum samples required

PATIENT CHARACTERISTICS:

Age:

• Adult

Performance status:

• Zubrod 0-1

Life expectancy:

• At least 8 weeks

Hematopoietic:

• Hemoglobin at least 10 g/dL (transfusions allowed)
• Absolute neutrophil count at least 1,500/mm^3
• Platelet count at least 100,000/mm^3

Hepatic:

• Bilirubin no greater than 2.0 mg/dL
• SGPT or SGOT no greater than 2 times normal

Renal:

• Creatinine no greater than 1.5 mg/dL
• BUN no greater than 25 mg/dL

Other:

• No known AIDS
• No other major medical illness or psychiatric impairment that would preclude study participation
• No active connective tissue disorders, including lupus and scleroderma
• No known multiple sclerosis
• No other malignancy within the past 3 years except nonmelanoma skin cancer or carcinoma in situ of the cervix or bladder
• Not pregnant or nursing
• Negative pregnancy test
• Fertile patients must use effective contraception

PRIOR CONCURRENT THERAPY:

Biologic therapy:

• Not specified

Chemotherapy:

• No prior chemotherapy or radiosensitizers for cancers of the head and neck

Endocrine therapy:

• Not specified

Radiotherapy:

• No prior radiotherapy to the head and neck except for T1 glottic tumors

Surgery:

• See Disease Characteristics
• No more than 5 weeks since prior surgery and recovered
• No concurrent ophthalmic surgery

Other:

• At least 30 days since prior participation in another clinical study
• No concurrent participation in another clinical study
• No concurrent systemic retinoids or herbal medicines
• No concurrent drugs that induce CytP4503A4 except enzyme-inducing anticonvulsant drugs