Carmustine Implants and O(6)-Benzylguanine in Treating Children With Recurrent Malignant Glioma

DISEASE CHARACTERISTICS: Histologically confirmed progressive supratentorial anaplastic astrocytoma or glioblastoma multiforme No multifocal disease or leptomeningeal dissemination of tumor No evidence of tumor crossing midline Limited intraventricular involvement Measurable unilateral mass at least 10 mm by contrast-enhanced MRI Received prior involved-field radiotherapy as a component of prior therapy Amenable to and in need of significant debulking PATIENT CHARACTERISTICS: Age 3 to 21 Performance status Karnofsky 60-100% OR Lansky 60-100% Life expectancy More than 8 weeks Hematopoietic Absolute neutrophil count greater than 1,000/mm3* Platelet count greater than 100,000/mm3* Hemoglobin greater than 8 g/dL (transfusions allowed) NOTE: * Transfusion independent Hepatic Bilirubin no greater than 1.5 times normal AST and ALT less than 3 times normal Albumin at least 2 g/dL No overt hepatic disease Renal Creatinine clearance no greater than 1.5 times normal OR Glomerular filtration rate greater than 70 mL/min No overt renal disease Cardiovascular No overt cardiac disease Pulmonary No overt pulmonary disease Other Neurological deficits must be stable for at least the past week No uncontrolled infection No known hypersensitivity to nitrosoureas or polyethylene glycol Not pregnant or nursing Negative pregnancy test Fertile patients must use effective contraception PRIOR CONCURRENT THERAPY: Biologic therapy At least 6 months since prior bone marrow transplantation More than 2 weeks since prior colony-stimulating growth factors (e.g., filgrastim (G-CSF), sargramostim (GM-CSF), or epoetin alfa) Chemotherapy No more than 2 prior cytotoxic chemotherapy regimens No more than 3 prior chemotherapy regimens total More than 3 weeks since prior myelosuppressive chemotherapy (6 weeks for nitrosoureas) and recovered Prior systemic carmustine (or other nitrosourea) allowed provided patient did not experience non-hematopoietic grade III/IV toxicity Endocrine therapy Concurrent dexamethasone allowed if on a stable dose for at least the past week Radiotherapy See Disease Characteristics At least 3 months since prior radiotherapy No prior craniospinal irradiation for metastatic disease Surgery See Disease Characteristics Prior biopsy or cytoreductive surgery allowed Other Concurrent anticonvulsants allowed No other concurrent anticancer or investigational drugs