Efficacy and morbidity of arc-therapy radiosurgery for cerebral arteriovenous malformations: a comparison with the natural history

PURPOSE: To report the results of arc-therapy radiosurgery for cerebral arteriovenous malformation (AVM) and to compare the adverse event rate with the rate expected from the natural history. METHODS AND MATERIALS: We performed a retrospective study of our 118 first patients with a mean follow-up of 46 months (range, 5-105 months). The AVMs had features indicating a poor prognosis at initial presentation and had already been treated by previous embolizations in 88% of patients. The mean volume of the targets was 7.4 cm3 (range, 0.3-28.3 cm3). The mean minimal and maximal dose was 17.7 Gy (range, 10-25 Gy) and 24.5 Gy (range, 17-36 Gy), respectively. RESULTS: The crude and 5-year actuarial rate of cure (total obstruction of the AVM shunt at angiography) was 54% (60 of 112) and 77%, respectively. The only independent prognostic factor of cure was the AVM volume (crude cure rate 67% for <7 cm3 vs. 35% for > or =7 cm3; p = 0.001). No patient died. Transient and permanent complications and hemorrhage occurred in 5%, 1.7%, and 6% of patients, respectively. The annual risk of an adverse event (hemorrhage or complication) was 3.9%. CONCLUSION: The results of our series showed that radiosurgery, performed alone or after prior shrinkage of the AVM by embolization, is both effective and well tolerated, with a rate of adverse events comparable to that expected from the natural history.