Vertebral compression fracture (VCF) after spine stereotactic body radiation therapy (SBRT): analysis of predictive factors.
OBJECTIVE
Vertebral compression fractures (VCFs) are increasingly observed after spine stereotactic body radiation therapy (SBRT). The aim of this study was to determine the risk of VCF after spine SBRT and identify clinical and dosimetric factors predictive for VCF. The analysis incorporated the recently described Spinal Instability Neoplastic Score (SINS) criteria.


METHODS
The primary endpoint of this study was the development of a de novo VCF (ie, new endplate fracture or collapse deformity) or fracture progression based on an existing fracture at the site of treatment after SBRT. We retrospectively scored 167 spinal segments in 90 patients treated with spine SBRT according to each of the 6 SINS criteria. We also evaluated the presence of paraspinal extension, prior radiation, various dosimetric parameters including dose per fraction (≥20 Gy vs <20 Gy), age, and histology.


RESULTS
The median follow-up was 7.4 months. We identified 19 fractures (11%): 12 de novo fractures (63%) and 7 cases of fracture progression (37%). The mean time to fracture after SBRT was 3.3 months (range, 0.5-21.6 months). The 1-year fracture-free probability was 87.3%. Multivariate analysis confirmed that alignment (P=.0003), lytic lesions (P=.007), lung (P=.03) and hepatocellular (P<.0001) primary histologies, and dose per fraction of 20 Gy or greater (P=.004) were significant predictors of VCF.


CONCLUSIONS
The presence of kyphotic/scoliotic deformity and the presence of lytic tumor were the only predictive factors of VCF based on the original 6 SINS criteria. We also report that patients with lung and hepatocellular tumors and treatment with SBRT of 20 Gy or greater in a single fraction are at a higher risk of VCF.
Division of Neurosurgery, Sunnybrook Health Sciences Centre, University of Toronto, Toronto, Ontario, Canada.
Marcelo V R
MV
Cunha
Ameen
A
Al-Omair
Eshetu G
EG
Atenafu
Giuseppina Laura
GL
Masucci
Daniel
D
Letourneau
Renee
R
Korol
Eugene
E
Yu
Peter
P
Howard
Fiona
F
Lochray
Leodante B
LB
da Costa
Michael G
MG
Fehlings
Arjun
A
Sahgal
D000293:Adolescent; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D000704:Analysis of Variance; D006528:Carcinoma, Hepatocellular / Q000378:metabolism / Q000601:surgery; D018450:Disease Progression; D005260:Female; D005500:Follow-Up Studies; D050815:Fractures, Compression / Q000175:diagnosis / Q000209:etiology*; D006801:Humans; D007738:Kyphosis / Q000175:diagnosis; D008113:Liver Neoplasms / Q000601:surgery; D008175:Lung Neoplasms / Q000601:surgery; D008279:Magnetic Resonance Imaging; D008297:Male; D008875:Middle Aged; D058958:Organs at Risk / Q000528:radiation effects; D011336:Probability; D016634:Radiosurgery / Q000009:adverse effects*; D012189:Retrospective Studies; D018570:Risk Assessment; D012600:Scoliosis / Q000175:diagnosis; D016103:Spinal Fractures / Q000175:diagnosis / Q000209:etiology*; D013125:Spinal Neoplasms / Q000175:diagnosis / Q000532:radiotherapy / Q000556:secondary*; D013997:Time Factors; D014057:Tomography, X-Ray Computed; D055815:Young Adult