To retrospectively evaluate the clinical benefit and imaging response of 
bevacizumab when used to treat refractory adverse radiation effects (ARE) after 
stereotactic radiosurgery. Twenty-nine patients with brain tumors or vascular 
malformations developed clinical and/or imaging evidence of ARE after SRS and 
were treated using bevacizumab. Patients received an average dose of 7.4 mg/kg 
over a mean of 5.7 weeks at a median of 16 months following SRS. Initial 
diagnosis, SRS dose, bevacizumab treatment protocols, magnetic resonance imaging 
T2/FLAIR and T1 paramagnetic contrast enhanced edema volumes were compared 
before and after bevacizumab administration. Ninety percent (18/20) with 
clinically symptomatic ARE had neurological improvement after bevacizumab 
therapy. Twenty-six patients had a decrease of 62 % of T2/FLAIR volumes and a 50 
% decrease in magnetic resonance imaging intravenous contrast enhancement 
volumes. Two patients showed progression of the T2/FLAIR and contrast 
enhancement volumes. One patient had progression of post-Gd-enhancement but 
regression of T2/FLAIR volume. Symptoms recurred in 11 of the 20 patients after 
discontinuing therapy. Patients who experienced a return of enhancement received 
a lower marginal dose during SRS. Our experience provides additional evidence 
that bevacizumab reduces both symptoms and reactive imaging changes in patients 
with ARE. After SRS, refractory ARE unresponsive to initial corticosteroids or 
other agents may benefit from a bevacizumab trial. The necessary duration and 
optimum dose of therapy is unknown and provides a further impetus to conduct a 
prospective trial.