Stereotactic body radiotherapy for non-spine bone metastases: A meta-analysis and international stereotactic radiosurgery society (ISRS) clinical practice guidelines.

Background: While SBRT to NSBM has become common, particularly in the oligometastatic population, the approach to treating non-spine bone metastases (NSBM) with stereotactic body radiotherapy (SBRT) varies widely across institutions and clinical trial protocols. We present a comprehensive systematic review of the literatures to inform practice recommendations on behalf of the International Stereotactic Radiosurgery Society (ISRS).

Methods: A systematic literature review was conducted in accordance with the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines. Studies with at least 10 patients receiving SBRT for NSBM were identified and meta-analyses were completed to estimate pooled local control and overall survival rates. Published guidelines on NSBM SBRT were reviewed and consolidated.

Results: There were 25 studies included for qualitative analysis and 18 studies for quantitative analysis consisting of 13 retrospective studies, 2 non-randomized prospective studies, 1 randomized phase 2/3 trial, and a subgroup analysis of a phase I trial. The pooled local control rates at 1 and 2 years were 95 % (95 % CI: 89 %-98 %) and 94 % (95 % CI: 86 %-98 %), respectively. Pooled overall survival rates at 1 year and 2 years were 84 % (95 % CI: 73 %-91 %) and 81 % (95 % CI: 45 %-95 %), respectively. Consensus was reached on recommendations to inform treatment simulation, target delineation, dose fractionation, and anatomic site-specific recommendations.

Conclusion: We present ISRS-endorsed consensus recommendations to inform best practice of SBRT to NSBM, which we found to be efficacious and associated with low rates of adverse events.