Inclusion Criteria

DISEASE CHARACTERISTICS:

- Histologically confirmed malignant glioma of 1 of the following subtypes:

- Low-grade glioma

- Anaplastic astrocytoma

- Anaplastic oligodendroglioma

- Glioblastoma multiforme

- Unifocal disease that is progressive or recurrent after prior radiotherapy and/or
chemotherapy

- Scheduled to undergo surgical resection

- Able to undergo maximal surgical resection of tumor mass

PATIENT CHARACTERISTICS:

- Karnofsky performance status 70-100%

- Mini Mental Status Exam ≥ 15

- Absolute neutrophil count ≥ 1,500/mm³

- Platelet count ≥ 100,000/mm³

- Creatinine ≥ 1.7 mg/dL

- BUN ≤ 2 times upper limit of normal (ULN)

- Transaminases ≤ 4 times ULN

- Not pregnant or nursing

- Fertile patients must use effective contraception during and for ≥ 1 month after
completion of study treatment

- No other medical illness that would preclude study treatment, including any of the
following:

- Serious infection

- Uncontrolled hypertension

- Unstable angina pectoris

- Uncontrolled cardiac dysrhythmia

PRIOR CONCURRENT THERAPY:

- See Disease Characteristics

- Recovered from all prior therapy

- At least 4 weeks since prior investigational drugs

- No more than 1 prior chemotherapy regimen

- No concurrent chemotherapy, biologic therapy, or radiotherapy

- No concurrent medications that may interact with imatinib mesylate or interfere with
hepatic cytochrome P450 system