Effect of bevacizumab on radiation necrosis of the central nervous system

Blocking vascular endothelial growth factor (VEGF) from reaching leaky capillaries is a logical strategy for treating radiation necrosis. Hence, we reasoned that bevacizumab may be an effective treatment for radiation necrosis of the brain. In this study, we attempted to differentiate radiation necrosis from recurrent malignant brain tumors by using positron emission tomography (PET) with L-[methyl-11 C] methionine (MET). Bevacizumab treatment was administered over 6 cycles for the treatment of radiation necrosis. Eleven patients with radiation necrosis of the brain were treated with bevacizumab on a 5 mg/kg biweekly regimen, for a total of 6 cycles. Radiation necrosis was diagnosed in all the patients on the basis of MET-PET. The accuracy of the MET-PET scan was evaluated by correlating its findings with the subsequent clinical course and MR spectroscopy findings. MRI studies were obtained before treatment and after completion of bevacizumab treatment. Of the 11 patients with radiation necrosis, neurological dysfunction was remarkably alleviated in 9 patients. Two patients demonstrated no remarkable alleviated in neurological dysfunction. Post-treatment MRI performed after the bevacizumab therapy showed a significant reduction in abnormalities in all 11 patients in both fluid-attenuated inversion-recovery and T1-weighted post-contrast MRI. We conclude that bevacizumab can decrease radiation necrosis significantly by decreasing capillary leakage and associated brain edema. (author)