RADT-39. CYBERKNIFE: THE CURRENT STATE OF LINAC AS TREATMENT FOR VESTIBULAR SCHWANNOMAS

Abstract

Abstract INTRODUCTION In the present study, we systematically review the extant literature describing CyberKnife radiosurgery (CKRS) as treatment for vestibular schwannoma (VS). We then perform pooled meta-analysis of long-term tumor control and hearing preservation rates reported across all retrospective observational series describing the efficacy of CKRS. METHODS We queried three databases to identify all primary retrospective studies reporting local tumor control and hearing preservation rates following CKRS for treatment of vestibular schwannoma. All studies returned across the three databases were subject to systematic screen according to pre-defined inclusion and exclusion criteria in a multi-step process performed by two investigators. RESULTS Following a comprehensive systematic search, a total of 15 studies comprising 2018 vestibular schwannoma patients were included. The proportion of females ranged from 30% to 60.3%, and the mean age of all 2,018 patients was 60.2 years. There were 64 patients who had neurofibromatosis type 2 (NF-2). Additionally, 309 patients had previously undergone surgical resection and/or radiosurgery for VS. In regard to CKRS treatment parameters, the marginal dose ranged from 1.9-25.78 Gy. The mean follow-up duration across the included studies was 40.0 months. Pooled rate of tumor control using the random effects model was 96% (95% CI: 95%-98%), and that of hearing preservation was 73% (95% CI: 66%-81%). The most common major complications following CKRS were trigeminal neuralgia, facial neuropathy, and hydrocephalus. CONCLUSIONS As studies on CyberKnife radiosurgery, one of the SRS modalities administered via LINAC, are far less common than studies on Gamma Knife radiosurgery for treatment of VS, more studies are needed in order to solidify the findings reported in the present meta-analysis. Although there are currently only 15 single-institution retrospective studies available in the neurosurgical literature, this study provides the most comprehensive and up-to-date analysis of highly relevant outcomes of interest in treatment of vestibular schwannoma via CyberKnife.