Clinical and radiological effects of Bevacizumab for the treatment of radionecrosis after stereotactic brain radiotherapy

Abstract Purpose The purpose of this multicenter retrospective study was to analyze the clinical and radiological effects of bevacizumab (BV) on radionecrosis (RN) that developed after stereotactic radiotherapy (SRT) for brain metastasis. Methods Forty patients with SRT related symptomatic brain RN treated in 10 radiation oncology centers were analyzed. The clinical response to BV treatment was categorized as follows: complete (no additional treatment required), partial (requiring either steroids or repeat BV), and unresponsive (requiring surgery). The radiological features of brain RN were analyzed in 10 patients whose serial MRI scans were available after corticosteroid and BV treatments. Results BV was used as a first line treatment in 11 (27.5%) and as a second line treatment in 29 (72.5%) of patients. The neurological symptoms regressed in 77.5% of patients after treatment with BV (45% complete response, 32.5% partial response). The median edema volume increased from 75.9 cc (range: 5.9-125.8 cc) at RN to 113.65 cc (range: 1.5-382.1 cc) after use of corticosteroids, representing a rate of 39.8% increase ( p = 0.074). However, after BV treatment the median volume of edema decreased to 19.5 cc (range: 0-163.3 cc) which represents a difference of 62.2% ( p = 0.041) from RN. Conclusion The use of BV caused clinical response rate of 77.5% and a good radiological response in corticosteroid unresponsive patients. The role of BV should be further investigated in prospective studies.