Overall, vertebral compression fracture is relatively uncommon after spine SBRT. What is the risk, though, among those with potentially unstable spine mets? This retrospective study identified 976 spine segments in 524 patients that were potentially unstable and were treated with SBRT. Potential instability was defined as a SINS score of 7-12 (median 9). Pre-existing compression fracture was present in 35.3%, 29.7% had received prior RT, and 26.7% had prior surgery. Epidural extension was present in 55.5%, and paraspinal extension in 52.8%. The most common regimen was 24 Gy in 2 fractions (35.2%) followed by 28 Gy in 2 fractions (24.4%), and 30 Gy in 4 fractions (28%). VCF occurred in 17.2% with roughly two-thirds of those (63.7%) happening without tumor progression. About half of the VCFs were new (50.6%) and the rest were progression of a baseline VCF. The strongest predictor of VCF was tumor progression. Other risk factors included baseline VCF, lumbar or thoracic location, no prior surgery or radiation, increasing CTV D90, and SINS of 10 or more. Those with a SINS of 7-9 had significantly lower risk of VCF than those with SINS of 10 or more. | Burgess, Int J Radiat Oncol Biol Phys 2026
