ABSTRACT
Single-fraction stereotactic radiosurgery (SRS) and 2–5 fraction stereotactic radiotherapy (hSRT) are widely used and efficacious treatments for brain/spine metastases, meningiomas, arteriovenous malformations, vestibular schwannomas, trigeminal neuralgia, and recurrent gliomas. The importance of clinical outcome data for assessing the risk of late complications including parenchymal brain radiation necrosis after SRS/hSRT is paramount. SRS/hSRT induced necrosis can usually be managed conservatively with observation in asymptomatic or minimally symptomatic patients. The most studied treatment-related factor related to brain radiation necrosis is the volume of tissue irradiated at or greater than a specific dose. Targeted therapy can impact radionecrosis risk when combined with SRS. Multiple studies indicate that combining immunotherapeutic checkpoint inhibitors with SRS may increase radionecrosis risk. Studies of bevacizumab for the prevention of radionecrosis in brain tumor patients undergoing dose-escalated radiation therapy or reirradiation have produced mixed results. Fractionation with hSRT, delivering biologically effective doses similar to single-fraction SRS, theoretically reduces risks of normal tissue injury.
