Inclusion Criteria

DISEASE CHARACTERISTICS:

- Histologically confirmed recurrent supratentorial glioblastoma multiforme, anaplastic
astrocytoma, or gliosarcoma

- Must be able to undergo surgical resection

- At least 1 bidimensionally measurable lesion documented on Gd-MRI within 72 hours
after surgical implantation of Gliadel wafers

- Not requiring immediate radiotherapy

PATIENT CHARACTERISTICS:

Age:

- 18 and over

Performance status:

- Karnofsky 70-100%

Life expectancy:

- Greater than 12 weeks

Hematopoietic:

- Absolute neutrophil count at least 1,500/mm^3

- Platelet count at least 125,000/mm^3

- Hematocrit at least 29%

Hepatic:

- Bilirubin less than 1.5 times upper limit of normal (ULN)

- SGOT or 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

Neurological:

- Must be neurologically stable

Other:

- HIV negative

- No AIDS-related illness

- No nonmalignant systemic disease that would make patient a poor medical risk

- No acute infection requiring intravenous antibiotics

- Not pregnant or nursing

- Negative pregnancy test 24 hours prior to study

- Effective contraception required of all fertile patients

PRIOR CONCURRENT THERAPY:

Biologic therapy:

- Not specified

Chemotherapy:

- No prior irinotecan

- At least 6 weeks since chemotherapy unless there is unequivocal evidence of tumor
progression after chemotherapy

Endocrine therapy:

- At least 1 week of nonincreasing dose of steroids prior to study

Radiotherapy:

- At least 6 weeks since radiotherapy unless there is unequivocal evidence of tumor
progression after radiotherapy

- No concurrent radiotherapy

Surgery:

- Not specified