DISEASE CHARACTERISTICS: Histologically proven malignant primary glioma Glioblastoma multiforme Anaplastic oligodendroglioma Gliosarcoma Mixed malignant glioma Anaplastic astrocytoma Clear evidence of tumor recurrence or progression by CT or MRI within 2 weeks prior to study after failing prior best surgical resection and radiation Surgically accessible tumor for which resection is indicated Tumors greater than 2.0 cm in diameter Tumor not extending into the ventricular system