Stereotactic Body Radiotherapy vs. Conventional Radiotherapy for Painful Bone Metastases: A Systematic Review and Meta-Analysis of Randomized Controlled Trials

Abstract

<h3>Purpose/Objective(s)</h3> As the superiority of stereotactic body radiotherapy (SBRT) over conventional external beam radiotherapy (cEBRT) remains controversial for pain palliation, we conducted a systematic review and meta-analysis of randomized controlled trials (RCTs). <h3>Materials/Methods</h3> A systematic review of literature was conducted in PubMed on January 22, 2022, which included prospective RCTs published to date. The inclusion criteria were as follows: (i) RCT comparing SBRT with cEBRT for bone metastases, and (ii) endpoint including pain response. The primary outcome of interest was the overall pain response (OR) rate of bone metastases at 3 months in intention-to-treat analysis. As a subgroup analysis, the analyses on OR were performed in spinal metastases. Pooling of effect sizes across studies was conducted using random-effects models in a meta-analysis of risk ratios. <h3>Results</h3> After 1,246 articles were screened, seven articles comprising 964 patients (522 and 442 patients in the SBRT and cEBRT arms, respectively) met the inclusion criteria. The OR rates of bone metastases at 3 months were 45% (95% confidence interval [CI], 31–60%) and 36% (95% CI, 25–49%) in the SBRT and cEBRT arms, respectively. These studies showed no significant difference between the two groups (risk ratio = 1.19; 95% CI, 0.93–1.53; p = 0.14). In the four studies included for the calculation of OR rates of spinal metastases at 3 months, the SBRT and cEBRT arms included 390 and 307 patients, respectively. The OR rates were 40% (95% CI, 21–62%) and 35% (95% CI, 26–44%) in the SBRT and cEBRT arms, respectively. There was no significant difference between the two groups (risk ratio = 1.14; 95% CI, 0.71–1.84; p = 0.44). The incidence of adverse effects and outcomes of health-related quality of life were comparable between the two arms. <h3>Conclusion</h3> The superiority of SBRT for bone metastases and spinal metastases over cEBRT for pain palliation was not confirmed in this meta-analysis. Although SBRT is a standard of care, treatment indications should not be blindly expanded.