title: Vertebral compression fracture after spine stereotactic body radiotherapy: a multi-institutional analysis with a focus on radiation dose and the spinal instability neoplastic score.
abstract: OBJECTIVE
  Vertebral compression fracture (VCF) is increasingly recognized as an adverse event after spine stereotactic body radiotherapy (SBRT). We report a multi-institutional study aimed at clarifying the risk and predictive factors associated with VCF.
  
  
  METHODS
  A total of 252 patients with 410 spinal segments treated with SBRT were included. The primary outcome was the development of VCF (a new VCF or progression of a baseline VCF). In addition to various patient-, treatment-, and tumor-specific factors, the Spinal Instability Neoplastic Scoring (SINS) system was applied to determine predictive value.
  
  
  RESULTS
  The median follow-up was 11.5 months (range, 0.03 to 113 months). The median and mean overall survival rates were 16 and 26 months, respectively. We observed 57 fractures (57 of 410, 14%), with 47% (27 of 57) new fractures and 53% (30 of 57) fracture progression. The median time to VCF was 2.46 months (range, 0.03 to 43.01 months), and 65% occurred within the first 4 months. The 1- and 2-year cumulative incidences of fracture were 12.35% and 13.49%, respectively. Multivariable analysis identified dose per fraction (greatest risk for ≥ 24 Gy v 20 to 23 Gy v ≤ 19 Gy), in addition to three of the six original SINS criteria: baseline VCF, lytic tumor, and spinal deformity, as significant predictors of VCF.
  
  
  CONCLUSIONS
  Caution must be observed when treating with ≥ 20 Gy/fraction, in particular, for patients with lytic tumor, spinal misalignment, and a baseline VCF. Frequent short-term follow-up is required, as nearly two thirds of all VCF occurred within the first 4 months. We also conclude that SINS may have utility in predicting patients at high risk of SBRT-induced VCF.
authors: Arjun Sahgal and Ameen Al-Omair, Princess Margaret Cancer Centre; Arjun Sahgal, Ameen Al-Omair, Marcelo Cunha, and Isabelle Thibault, Sunnybrook Health Sciences Centre; Eshetu G. Atenafu, University Health Network; Michael G. Fehlings, Toronto Western Hospital, University of Toronto, Toronto, Ontario, Canada; Sam Chao, Ehsan H. Balagamwala, Lilyana Angelov, and John Suh, Cleveland Clinic, Cleveland, OH; Nicholas Boehling, Paul Brown, Laurence D. Rhines, and Eric Chang, MD Anderson Cancer Center, University of Texas, Houston, TX; and Eric Chang, University of Southern California, Los Angeles, CA.
authors: Arjun
authors: A
authors: Sahgal
authors: Eshetu G
authors: EG
authors: Atenafu
authors: Sam
authors: S
authors: Chao
authors: Ameen
authors: A
authors: Al-Omair
authors: Nicholas
authors: N
authors: Boehling
authors: Ehsan H
authors: EH
authors: Balagamwala
authors: Marcelo
authors: M
authors: Cunha
authors: Isabelle
authors: I
authors: Thibault
authors: Lilyana
authors: L
authors: Angelov
authors: Paul
authors: P
authors: Brown
authors: John
authors: J
authors: Suh
authors: Laurence D
authors: LD
authors: Rhines
authors: Michael G
authors: MG
authors: Fehlings
authors: Eric
authors: E
authors: Chang
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D005260:Female; D050815:Fractures, Compression / Q000209:etiology* / Q000473:pathology; D006801:Humans; D008297:Male; D008875:Middle Aged; D016634:Radiosurgery / Q000009:adverse effects*; D016103:Spinal Fractures / Q000209:etiology* / Q000473:pathology; D013125:Spinal Neoplasms / Q000473:pathology* / Q000601:surgery*; D013131:Spine / Q000473:pathology / Q000528:radiation effects; D016019:Survival Analysis
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