Is the CyberKnife radiosurgery system effective and safe for patients? An umbrella review of the evidence

Background: The CyberKnife system combines real-time image guidance and a dynamic tracking system to implement frameless radiotherapy. This umbrella review is aimed to evaluate the effectiveness and safety of CyberKnife. Methods: A comprehensive search of health technology assessments and systematic reviews was performed among the Embase, PubMed and other grey databases until July 2020. Treatment outcomes were extracted, and the quality of included studies were assessed using AMSTAR-2. Results: Nineteen studies were eligible. CyberKnife not only had a wide range of applications, long overall survival and great local control, but also had a limited toxicity and good cost-effectiveness compared with other radiotherapy equipment. Conclusion: Despite the relatively low quality of the evidence, our findings can still provide a decision reference for policymakers. Plain language summary An umbrella review on the effectiveness and safety of the CyberKnife system was performed by comprehensively searching for all related publications. The CyberKnife system had excellent effect on treatment of cancer and some noncancer diseases, with limited toxicity. Additionally, it was a cost-effective treatment compared with other types of radiotherapy. Despite the relatively low quality of the included evidence, our findings can still provide a comprehensive decision reference for policymakers of patients, government and hospitals.