Clinical Outcomes Following Stereotactic Body Radiation Therapy (SBRT) for Non-Spinal Bone Metastases: A Systematic Review and Meta-Analysis

Purpose/Objective(s)

There is limited data available on clinical outcomes following stereotactic body radiation therapy (SBRT) for non-spinal bone metastases. As such, we aimed to perform a systematic review and meta-analysis to characterize local control (LC), overall survival (OS), pain control, and toxicity following SBRT.

Materials/Methods

A PICOS/PRISMA/MOOSE selection criterion was utilized to identify studies. Primary outcomes were 1-year LC and incidences of acute and late Grade 3-5 toxicities. The secondary outcomes were 1-year OS and pain control at 3 months. Weighted random effects meta-analyses were conducted to estimate effect sizes. Mixed effects weighted regression models were utilized to assess for correlations between median biologically effective dose (BED₁₀), LC, and toxicity incidence.

Results

We identified 460 patients with 580 non-spinal bone lesions across 9 studies treated with SBRT. The median age was 64 years (range: 36-91). The most common primaries were prostate (28.7%), lung (23.0%), renal cell carcinoma (16.5%), and breast (14.3%). For those on information with weight-bearing status, 424/571 lesions (74.3%) were weight-bearing. The median dose and fractionation were 35 Gy/5 fractions with a median BED₁₀ of 59.5 Gy (range: 26.4-81.6 Gy). The estimated 1-year OS rate was 71.0% (95% CI: 51.7-87.0%). The estimated 1-year LC rate was 94.6% (95% CI: 87.0-99.0%). The estimated combined acute and late Grade 3-5 toxicity rate was 0.5% (95% CI: 0-5.0%). The estimated 3-month combined partial and total pain response rate following SBRT was 87.7% (95% CI: 55.1-100.0%). We did not note a correlation between BED₁₀ and LC, toxicity indigence, or pain-response rates.

Conclusion

SBRT resulted in excellent LC as well and palliative outcomes with minimal related toxicity. Additional dose escalation was not found to be associated with either improved outcomes or additional toxicity. Prospective investigations are warranted to further examine the role of SBRT for patients with non-spinal bone metastases in order to inform the ideal dose/fractionation schema and approaches to planning.