DISEASE CHARACTERISTICS: Histologically proven glioblastoma multiforme, anaplastic astrocytoma, or anaplastic mixed glioma Progressive or recurrent disease following radiotherapy (54-64 Gy) and/or chemotherapy Tumor recurrence must have anatomic characteristics that allow safe and reasonable surgical intervention Measurable disease by serial MR or CT imaging No Li-Fraumeni syndrome or known germline defect in p53 gene No radiographically or surgically proven gliomatosis cerebri No tumors requiring immediate excision due to impending neurologic decline

PATIENT CHARACTERISTICS: Age: 18 and over Performance status: Karnofsky 60-100% Life expectancy: Not specified Hematopoietic: WBC at least 3,000/mm3 Absolute neutrophil count at least 1,000/mm3 Platelet count at least 100,000/mm3 Hematocrit at least 25% Hepatic: Bilirubin less than 1.5 mg/dL SGOT and SGPT less than 2.5 times upper limit of normal (ULN) PT or PTT no greater than ULN Renal: Creatinine no greater than 1.7 mg/dL Cardiovascular: No uncontrolled hypertension No uncontrolled or unstable angina pectoris No uncontrolled cardiac dysrhythmia Other: Not pregnant or nursing Negative pregnancy test Fertile patients must use effective contraception during and for 6 months after study HIV negative No other active malignancy within the past 5 years except curatively treated basal or squamous cell skin cancer or carcinoma in situ of the cervix No uncontrolled or serious concurrent infection or other serious medical illness that would preclude study therapy No viral syndrome diagnosed within 2 weeks prior to study No other underlying medical condition that would increase risk of study or obscure interpretation of adverse results No active adenoviral infection

PRIOR CONCURRENT THERAPY: Biologic therapy: At least 3 weeks since prior biologic therapy and recovered No concurrent biologic therapy Chemotherapy:

See Disease Characteristics No more than 1 prior chemotherapy regimen At least 3 weeks since prior chemotherapy (6 weeks for nitrosoureas) and recovered No prior interstitial chemotherapy such as Gliadel wafer implantation for present brain tumor No concurrent chemotherapy Endocrine therapy: At least 3 weeks since prior hormonal therapy and recovered No concurrent hormonal therapy Radiotherapy: See Disease Characteristics No prior brachytherapy for present brain tumor At least 3 months since other prior radiotherapy and recovered No concurrent radiotherapy Surgery: See Disease Characteristics No prior radiosurgery for present brain tumor At least 3 weeks since other prior oncologic surgery No other concurrent oncologic surgery Other: No other concurrent investigational drugs