2555 - Comparative Efficacy and Safety of Stereotactic Body Radiation Therapy Dose-Fractionation Regimens for Spinal Metastases: A Systematic Review and Network Meta-Analysis of Randomized Controlled Trials

S. F. Lee¹, H. C. Y. Wong², S. Caini³, A. W. Chan⁴, G. N. Marta^5,6, S. Ryu⁷, D. Rades⁸, C. B. Simone II⁹, P. A. S. Johnstone¹⁰, A. Rembielak¹¹, L. Khan¹², E. Oldenburger¹³, S. Raman¹⁴, S. S. Tse¹⁵, E. Chow⁴, and P. Hoskin¹⁶; ¹Department of Radiation Oncology, National University Cancer Institute, Singapore, Singapore, ²Department of Oncology, Princess Margaret Hospital, Kwai Chung, Hong Kong, ³Institute for Cancer Research, Prevention, and Clinical Network (ISPRO), Florence, Italy, ⁴Department of Radiation Oncology, Odette Cancer Centre, Sunnybrook Health Sciences Centre, University of Toronto, Toronto, ON, Canada, ⁵Department of Radiation Oncology, Hospital Sírio-Libanês, Sao Paulo, Brazil, ⁶Department of Radiation Oncology Hospital Sírio-Libanês and Instituto do Câncer do Estado de São Paulo - Faculdade de Medicina da Universidade de São Paulo, Sao Paulo, Brazil, ⁷Department of Radiation Oncology, Stony Brook University Hospital, Stony Brook, NY, ⁸Department of Radiation Oncology, University of Lübeck, Lübeck, Germany, ⁹New York Proton Center, New York, NY, ¹⁰H. Lee Moffitt Cancer Center & Research Institute, Tampa, FL, ¹¹Division of Cancer Sciences, University of Manchester, Manchester, United Kingdom, ¹²University of Toronto, Toronto, ON, Canada, ¹³Department of Radiation Oncology, University Hospitals Leuven, Leuven, Belgium, ¹⁴Radiation Medicine Program, Princess Margaret Cancer Centre, Toronto, ON, Canada, ¹⁵Department of Clinical Oncology, Queen Elizabeth Hospital, Hospital Authority, Hong Kong, Hong Kong, ¹⁶Mount Vernon Cancer Centre, Middlesex, United Kingdom

Purpose/Objective(s): Stereotactic body radiation therapy (SBRT) represents a paradigm shift in the precision oncologic management of spinal metastases, leveraging advanced image-guidance and motion management techniques to deliver ablative doses with sub-millimetric accuracy. This study assesses the comparative efficacy and safety of various SBRT regimens for spinal metastases using a network meta-analysis (NMA) approach, integrating both direct and indirect evidence from randomized controlled trials (RCTs). Materials/

Methods: A comprehensive search of Ovid MEDLINE, Embase, and the Cochrane Central Register of Controlled Trials was conducted through March 1, 2023 to identify RCTs comparing SBRT with conventional external beam radiotherapy (cEBRT) in treating spinal metastases. The primary outcomes included overall and complete pain response, local tumor progression, and overall survival. Risk ratios (RR) and hazard ratios (HR) with 95% confidence intervals (CI) were estimated using a random-effects model. Heterogeneity was assessed with the Cochran Q and I² statistics, and the P-score method was employed to rank treatment efficacy.
Results: Three RCTs involving 642 patients were included. The SBRT regimens were 24 Gy in a single fraction, 24 Gy in 2 daily fractions, and 16 or 18 Gy in a single fraction, all compared against cEBRT. The regimen of 16 or 18 Gy in a single fraction showed a statistically significant lower overall pain response at 3 months compared to 24 Gy in 2 daily fractions (RR 0.58, 95% CI, 0.37–0.89; P=0.013), with no significant differences at 6 months. Complete pain response at 3 and 6 months did not significantly differ across SBRT dose-fractionations, with data missing from one trial. Side effects were rare and similar across regimens, although 24 Gy in 2 fractions was associated with fewer compression fractures compared to 24 Gy in a single fraction (RR 0.11, 95% CI, 0.01–0.98; P=0.047). There were no significant differences in local progression and overall survival at 6 months across fractionation regimens.
Conclusion: This NMA suggests that different SBRT regimens offer comparable safety profiles and efficacy for the treatment of spinal metastases, with specific dose-fractionations showing advantages in certain outcomes. These findings underscore the necessity of tailored treatment strategies to optimize patient outcomes. Future research should prioritize elucidating patient and disease characteristics that predict the most benefit from specific SBRT protocols, thereby enhancing personalized care in spinal metastases management.