NCMP-03. SHORT AND LONG TERM EFFICACY OF BEVACIZUMAB THERAPY FOR RADIATION NECROSIS IN BRAIN METASTASES

Abstract

Abstract PURPOSE Brain radionecrosis (RN) is a frequent, and often life devastating complication of stereotactic radiotherapy (SRS) for brain metastases. There is no standard treatment for RN. Bevacizumab is often proposed although data regarding its efficacy is limited. We performed a retrospective study to evaluate the short and long-term efficacy of bevacizumab in RN. METHODS We included all the patients who received bevacizumab for RN developed after treatment with SRS for brain metastases. Patients treated in our institution between 31/07/2018 and 31/07/2022 were enrolled into the study. Clinical and radiographic evaluations, immediately, 6, 12 and 24 months after completion of bevacizumab were evaluated. Response was assessed using RANO criteria. Changes in volume lesion were calculated using Brain Lab navigator system. RESULTS 24 patients were included in the study. Median time from diagnosis of RN to treatment with bevacizumab was 5.1 months. According to RANO criteria first MRI performed after completion of treatment with bevacizumab showed a partial or complete response in 34 % of the patient and a stable disease in 41% of the patient. Volumetric measurements demonstrated significant (above 25%) diminution in the volume of the lesion in 66% of patients. Clinical improvement in neurological symptoms was revealed in 41 % of patients and steroid dosage was reduced in 50% of patients. Among the patients with a stable disease in the first MRI after bevacizumab, 27% demonstrated partial or complete response at the following 6 months MRI. During the entire follow-up period, a regrowth of RN occurred in 45% of patients who demonstrated a partial or complete response in the first MRI after bevacizumab. CONCLUSION Bevacizumab is an effective therapy for of RN, with high response rate within the first 6 first months after treatment. However regrowth of radionecrosis is occurs frequently during long term follow-up.