Morbidity of Single-Fraction Spine Radiosurgery for Metastatic Disease.

person Ulysses Grant Gardner Johns Hopkins Hospital, Baltimore, MD info_outline Ulysses Grant Gardner, Shearwood McClelland

Authors person Ulysses Grant Gardner Johns Hopkins Hospital, Baltimore, MD info_outline Ulysses Grant Gardner, Shearwood McClelland Organizations Johns Hopkins Hospital, Baltimore, MD, University Hospitals Seidman Cancer Center, Department of Radiation Oncology, Case Western Reserve University School of Medicine, Cleveland, OH Abstract Disclosures Research Funding No funding received None. Background: The optimal management of metastatic spine disease involves radiation therapy, with stereotactic radiosurgery (SRS) utilization having increased in adoption while proving to be efficacious and safe. Spine SRS morbidity (fatigue, dermatitis, nausea and esophagitis) is generally mild and depends on the spinal vertebral level(s) treated. More severe adverse events such as vertebral compression fracture (VCF), radiation-induced myelopathy, and tracheoesophageal (TE) fistula have been documented. The potential benefits of single-fraction SRS (sfSRS) over multi-fraction SRS include increased patient convenience, decreased financial toxicity, and increased treatment completion rates. These benefits may potentially be overshadowed by the morbidity of sfSRS versus multifraction SRS. In this analysis, we perform the first comprehensive examination of sfSRS morbidity in the treatment of spinal lesions. Methods: An extensive search of the PubMed database was undertaken through 2/2/23 to find studies examining spinal sfSRS. Search parameters included the terms “single-fraction, spine, radiation SRS OR SBRT” Articles including multi-fractionated regimens only, reviewed sites outside of the spine, or did not report on clinical outcomes/toxicities were excluded. Results: 17 articles met initial inclusion criteria; 9 were added from references for a total of 26 articles comprising at least 2,699 patients (one study reported the number of tumors, not patients). Dose ranges for single-fraction SRS were 8-26 Gy. Commonly noted toxicities were fatigue, nausea/vomiting, and dermatitis which were no worse than moderate/minimal, not requiring invasive intervention. The overall rate of VCF was 16.2%, with an increased propensity at >20 Gy. The proportion of reported segments requiring surgical intervention (operative stabilization, vertebroplasty/kyphoplasty) for VCF after single-fraction SRS was 20.2% (33/163). The rate of TE fistula at 25 Gy was 8.3%, with an overall rate (dose range = 10-28 Gy) of 1.3% with up to 12-years of follow-up. In patients receiving median dose of 24 Gy, the rate of severe esophagitis was 6.8%, myositis was 1.3% (at 1-year) and 8.3% (at 5-years). The rate of peripheral nervous system injury was 2.5% (at 18-26 Gy) and pain flare was 8% (at 16-24 Gy). The rate of ureteral and esophageal stricture was 1.9% each in patients receiving 12-24 Gy. Conclusions: VCF is the most commonly reported severe adverse events with single-fraction spine SRS, particularly for doses > 20 Gy. 80% of VCFs can be successfully managed without invasive intervention. Other severe adverse events are rare – particularly for < 20 Gy – but require post-SRS monitoring to expediently and efficiently intervene if necessary. These findings indicate that single-fraction spine SRS to < 20 Gy is safe with minimal morbidity. Further study regarding the efficacy of such dosing is being evaluated in ongoing clinical trials.