2484 - Incidence and Risk Factors Associated with Need for Treatment of Vertebral Compression Fractures after Spine Stereotactic Radiosurgery

J. J. Bai¹, S. T. Chao², L. Angelov³, D. S. Buchberger², J. H. Suh², E. S. Murphy², S. D. Pestak², J. L. Barnhart², S. Johnson², and E. H. Balagamwala²; ¹Case Western Reserve University School of Medicine, Cleveland, OH, ²Department of Radiation Oncology, Cleveland Clinic Foundation, Cleveland, OH, ³Department of Neurological Surgery, Cleveland Clinic Foundation, Cleveland, OH

Purpose/Objective(s): Vertebral compression fracture (VCF) is a known complication after spine stereotactic radiosurgery (sSRS). However, the occurrence of treatment of VCFs is not well characterized. This study aims to describe the incidence and risk factors associated with treatment of VCF after sSRS. Materials/

Methods: 1,689 spinal segments in 605 patients who received sSRS were evaluated from an IRB-approved retrospective single-institution database. The primary endpoint was occurrence of VCF treatment. Median overall survival and median time from VCF to treatment were calculated by Kaplan-Meier analysis. Logistic regression was used to assess the association between various clinical and treatment factors and occurrence of VCF treatment.
Results: 114 spinal segments (6.7%; 114/1689) in 99 patients developed VCFs after sSRS. Median follow-up was 16.9 months (range, 1.3 – 160.2). 65% of patients were male, median age at treatment was 62 years (range, 30 – 88.1), median prescription dose was 16 Gy in 1 fraction (range, 10-30 Gy/1-5 fractions) , and median KPS was 80 (range, 50 – 100). Most common primary cancers were renal (24%), lung (16%), and breast (12%). Out of the 114 fractures, 40% (45/114) were new, while 60% (69/114) had fracture progression. Narcotic use occurred in only 20% of fractures that did not require further treatment, while narcotics were used in 80% of VCFs in the treatment group. Only 25 segments with VCFs (22%; 25/114) in 23 patients underwent or were offered treatment (decompression 28%, fusion 40%, instrumentation and fixation 16%, posterior column osteotomy 4%, contraindications to surgery 16%, patient declined 4%, patient died before surgery 8%). Median time from VCF to treatment was 21 days (range, 0 – 334). Median overall survival from sSRS and development of VCF was 20.1 and 15.9 months respectively. There were no significant differences in median overall survival from sSRS (p = 0.08) and fracture (p = 0.3) between the VCF treated group and VCF non-treated group. Cervical, thoracic, and lumbar fracture locations were not significant risk factors for treatment of VCF (p > 0.05). On multivariate analysis, younger age (OR = 0.95; p = 0.04), pain flare after sSRS (OR = 7.76; p = 0.02), shorter time from sSRS to fracture (OR = 0.99; p = 0.03), higher total prescription dose (OR = 1.35; p = 0.03), and increased narcotic use after fracture (OR = 25.40; p < 0.01) were significantly associated with the occurrence of VCF treatment.
Conclusion: Although VCF is a relatively uncommon complication of sSRS, the need for treatment after VCF is infrequent. Risk factors for treatment of VCF include younger age, pain flare after sSRS, shorter time from sSRS to fracture, higher total prescription dose, and narcotics use after fracture. Providers may use these risk factors to identify patients at highest risk of needing treatment for their VCF.