Cerebral radiation necrosis successfully treated with high-dose bevacizumab

Cerebral radiation necrosis (CRN) is a late complication that can occur after the treatment of a brain tumor with focal radiation therapy, particularly stereotactic radiosurgery (SRS). Since an excessive production of vascular endothelial growth factor (VEGF) from necrotic lesions is a possible etiology of radiation necrosis, the anti-VEGF antibody bevacizumab has been reported as an effective treatment option. We report a case of a 71-year-old Japanese male with CRN following SRS, successfully treated with bevacizumab. He had presented with aphasia and right lower-limb muscle weakness 6 years after a left upper lobectomy for lung adenocarcinoma. Head magnetic resonance imaging (MRI) showed a metastatic brain tumor in the left temporal lobe. A craniotomy and pre- and post-operative SRS treatments were performed to relieve his neurological symptoms. Although initial symptom improvement was observed, the patient developed lower-limb muscle weakness and aphasia symptoms 7 months after the last SRS treatment. ¹¹C-methionine positron emission tomography (PET) and ¹⁸F-fluorodeoxyglucose PET scans showed no abnormal uptake, leading to a diagnosis of CRN. The patient was treated with bevacizumab 15 mg/kg every 3 weeks for six cycles. The bevacizumab treatment resulted in an improvement of neurological symptoms and lesions showing gadolinium-enhancing effects and high-signal areas on T2-weighted fluid attenuated inversion recovery on MRI. The improvement was maintained 44 months after the completion of the last bevacizumab treatment. Although no definitive number of cycles and dosage of bevacizumab for CRN have been established, this case suggests that administering six cycles of bevacizumab may prevent long-term recurrence of CRN.