DISEASE CHARACTERISTICS: Histologically confirmed malignant glioma, including: Anaplastic astrocytoma Glioblastoma Evidence of recurrence by MRI and positron emission tomography despite primary treatment that included radiotherapy with or without chemotherapy Stereotactically accessible tumor Solitary tumor preferred Largest tumor surgically accessible for debulking if multifocal disease Not adjacent to optic chiasm or brain stem No subependymal spread No herniation or marked midline shift Consent for autopsy required