title: Risk of fracture after single fraction image-guided intensity-modulated radiation therapy to spinal metastases.
abstract: OBJECTIVE
  Single-fraction image-guided intensity-modulated radiation therapy (IG-IMRT) allows for tumoricidal treatment of traditionally radioresistant cancers while sparing critical adjacent structures. Risk of vertebral fracture after IG-IMRT for spinal metastases has not been defined.
  
  
  METHODS
  We evaluated 62 consecutive patients undergoing single fraction IG-IMRT at 71 sites for solid organ metastases. A neuroradiologist and three spine surgeons evaluated prospectively obtained magnetic resonance/computed tomography (CT) imaging studies for post-treatment fracture development and tumor recurrence.
  
  
  RESULTS
  Fracture progression was noted in 27 vertebrae (39%). Multivariate logistic regression analysis showed that CT appearance, lesion location, and percent vertebral body involvement independently predicted fracture progression. Lesions located between T10 and the sacrum were 4.6 times more likely to fracture than were lesions above T10 (95% CI, 1.1 to 19.7). Lytic lesions were 6.8 times more likely to fracture than were sclerotic and mixed lesions (95% CI, 1.4 to 33.3). As percent vertebral body involvement increased, odds of fracture also increased. Patients with fracture progression had significantly higher narcotic use, change in Karnofsky performance score, and a strong trend toward higher pain scores. Local tumor progression occurred in seven patients and contributed to one fracture. Obesity, posterior element involvement, bisphosphonate use, and local kyphosis did not confer increased risk.
  
  
  CONCLUSIONS
  Vertebral fracture is common after single fraction IG-IMRT for metastatic spine lesions. Lytic disease involving more than 40% of the vertebral body and location at or below T10 confer a high risk of fracture, the presence of which yields significantly poorer clinical outcomes. These results may help clinicians identify high-risk patients who would benefit from prophylactic vertebro- or kyphoplasty.
authors.affiliation: Department of Orthopedic Surgery, Mayo Clinic, Rochester, MN, USA.
authors.forename: Peter S
authors.initials: PS
authors.lastname: Rose
authors.forename: Ilya
authors.initials: I
authors.lastname: Laufer
authors.forename: Patrick J
authors.initials: PJ
authors.lastname: Boland
authors.forename: Andrew
authors.initials: A
authors.lastname: Hanover
authors.forename: Mark H
authors.initials: MH
authors.lastname: Bilsky
authors.forename: Josh
authors.initials: J
authors.lastname: Yamada
authors.forename: Eric
authors.initials: E
authors.lastname: Lis
mesh_terms: D005260:Female; D006801:Humans; D008279:Magnetic Resonance Imaging; D008297:Male; D008875:Middle Aged; D050397:Radiotherapy, Intensity-Modulated / Q000009:adverse effects*; D012306:Risk; D012307:Risk Factors; D016103:Spinal Fractures / Q000175:diagnosis / Q000209:etiology*; D013125:Spinal Neoplasms / Q000532:radiotherapy* / Q000556:secondary; D014057:Tomography, X-Ray Computed