Inclusion Criteria

DISEASE CHARACTERISTICS:

- Histologically confirmed newly diagnosed supratentorial glioblastoma multiforme by
surgical biopsy or excision

- No gliomas graded less than glioblastoma multiforme

- No recurrent malignant gliomas

- No tumor foci below the tentorium or beyond the cranial vault

- Study therapy must begin ≤ 5 weeks after surgery

PATIENT CHARACTERISTICS:

Age

- 18 and over

Performance status

- Zubrod 0-1

Life expectancy

- At least 8 weeks

Hematopoietic

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

- Platelet count ≥ 100,000/mm^3

- Hemoglobin ≥ 10 g/dL*

- Hematocrit ≥ 30%* NOTE: *Transfusion allowed

Hepatic

- Bilirubin ≤ 0.5 mg/dL

- ALT or AST ≤ 2 times upper limit of normal

Renal

- Creatinine ≤ 1.5 mg/dL

- BUN ≤ 25 mg/dL

Other

- Not pregnant or nursing

- Negative pregnancy test

- Fertile patients must use effective double-barrier contraception during and for 2
months after study participation

- No AIDS

- No other malignancy within the past 5 years except nonmelanoma skin cancer or
carcinoma in situ of the cervix or bladder

- No other major medical illness or psychiatric impairment that would preclude study
participation

PRIOR CONCURRENT THERAPY:

Biologic therapy

- No concurrent sargramostim (GM-CSF)

Chemotherapy

- No other concurrent chemotherapy

Endocrine therapy

- Concurrent steroid therapy allowed provided patient is on a stable or decreasing dose
for at least 2 weeks before study entry

Radiotherapy

- No prior radiotherapy to the head or neck resulting in overlap of radiotherapy fields

- Prior radiotherapy for stage T1 glottic cancer allowed

Surgery

- See Disease Characteristics

- Recovered from prior surgery

Other

- No enzyme-inducing antiepileptic drugs within 14 days before the initiation of
irinotecan

- Concurrent non-enzyme-inducing antiepileptic drugs allowed