Inclusion Criteria

DISEASE CHARACTERISTICS: Histologically proven grade IV astrocytoma or glioblastoma
multiforme confined to 1 or both hemispheres of the brain Confirmation of histology by NIH
neuropathology review required MRI or CT completed within 3 weeks of initial evaluation No
clinically apparent leptomeningeal metastases No uncontrolled seizures despite standard
anticonvulsant therapy No history of epilepsy diagnosed a year or more before glioblastoma

PATIENT CHARACTERISTICS: Age: Over 18 Performance status: Karnofsky 80-100% OR ECOG 0-1
Life expectancy: More than 3 months Hematopoietic: WBC at least 3,500/mm3 Absolute
granulocyte count at least 900/mm3 Platelet count at least 100,000/mm3 Hemoglobin at least
10 g/dL No hematologic disease requiring treatment Hepatic: Liver function tests no
greater than 2.5 times upper limit of normal No hepatic disease requiring treatment Renal:
Creatinine no greater than 1.3 mg/dL OR Creatinine clearance at least 95 mL/min No renal
disease requiring treatment Cardiovascular: No history of hospitalization or medication
for: Cardiovascular disease with LVEF 45% or less Myocardial infarction Arrhythmia
Coronary artery disease Angina Congestive heart failure Stroke No thromboembolic disease
requiring treatment Pulmonary: No history of hospitalization or medication for chronic
obstructive pulmonary disease or asthma Other: No peptic ulcer disease or inflammatory
bowel disease within the past 2 years No documented history of intolerance to
methylxanthines (e.g., allergic or serious adverse reactions) No history of psychiatric or
medical illness that would preclude therapy No other malignancy within the past 5 years
except basal cell skin cancer or carcinoma in situ of the cervix No contraindication to
serial CT or MRI (e.g., logistical problems, noncompliance, contrast allergies) Not
pregnant or nursing Negative pregnancy test

PRIOR CONCURRENT THERAPY: Biologic therapy: Not specified Chemotherapy: No prior
chemotherapy Endocrine therapy: Not specified Radiotherapy: No prior radiotherapy Surgery:
Prior biopsy or subtotal or near-total resection allowed At least 7-10 days but no more
than 3 months since prior surgery and/or biopsy Other: No recent methylxanthine-containing
medications No concurrent anticoagulants or methylxanthines (e.g., aspirin, nonsteroidal
antiinflammatory drugs, warfarin, heparin, theophylline, aminophylline, theobromine) for
preexisting medical conditions