Efficacy of Short-Course Bevacizumab for Brain Tumor Radiation Necrosis with a Volumetric Analysis

Objective Radiation necrosis (RN) is a challenging complication of cranial irradiation, often requiring corticosteroids for management. This study evaluates the clinical and radiologic efficacy of a short-course bevacizumab (BEV) regimen for brain tumor RN, with a volumetric assessment. Methods We retrospectively analyzed 11 patients with magnetic resonance imaging–confirmed RN who received 2 or 3 cycles of BEV (7.5 mg/kg every 3 weeks). Volume changes of nonenhancing RN, enhancing RN, perilesional edema, and total lesion (RN + edema) were quantified at 4 time points (pretreatment, start, end, and post-treatment) using artificial intelligence–assisted volumetric analysis (DeepBratumIA). Clinical outcomes were assessed using Eastern Cooperative Oncology Group performance status and changes in corticosteroid use. Results Clinical improvement or stabilization was observed in 91% of patients, with steroid use decreasing from 91% at baseline to 36% at treatment completion. Median enhancing RN volume significantly decreased from 5.1 cm 3 –1.2 cm 3 ( P = 0.031), while nonenhancing RN volume showed a nonsignificant change (2.3 cm 3 –2.0 cm 3 , P = 0.414). Perilesional edema volume markedly declined from 65 cm 3 –18 cm 3 ( P = 0.001), and total lesion volume decreased from 69 cm 3 –21 cm 3 ( P = 0.001). No statistically significant differences were observed between steroid-maintained and steroid-discontinued groups in the magnitude of volume change at any time point. Partial volumetric rebound occurred post-treatment, but most patients maintained clinical benefit. Conclusions This study suggests the clinical and radiologic efficacy of short-course BEV as a practical steroid-sparing strategy for RN management.