Clinical outcomes following stereotactic body radiation therapy (SBRT) for Non-Spinal Bone Metastases: A Systematic Review and Meta-Analysis

BACKGROUND:There is limited data available on clinical outcomes following stereotactic body radiation therapy (SBRT) for non-spinal bone metastases. We performed a systematic review and meta-analysis to characterize local control (LC), overall survival (OS), pain response rates, and toxicity following SBRT. METHODS:Primary outcomes were 1-year LC, incidences of acute and late Grade 3-5 toxicities, and overall pain response rate at 3 months. The secondary outcome was 1-year OS. The Newcastle-Ottawa scale was employed for assessment of study bias, with a median score of 5⋆ for included studies (range: 4-8). Weighted random effects meta-analyses were conducted to estimate effect sizes. RESULTS:We identified 528 patients with 597 non-spinal bone lesions across 9 studies, 1 prospective and 8 retrospective observational, treated with SBRT. The estimated 1-year LC rate was 94.6% (95% CI: 87.0-99.0%). The estimated 3-month combined partial and complete pain response rate following SBRT was 87.7% (95% CI: 55.1-100.0%). The estimated combined acute and late Grade 3-5 toxicity rate was 0.5% (95% CI: 0-5.0%) with an estimated pathologic fracture rate of 3.1% (95% CI: 0.2-9.1%). The estimated 1-year OS rate was 71.0% (95% CI: 51.7-87.0%). CONCLUSIONS:SBRT resulted in excellent LC and palliation of symptoms with minimal related toxicity. Prospective investigations are warranted to further characterizes long-term outcomes with SBRT for patients with non-spinal bone metastases.