title: Fractures of the sacrum after chemoradiation for rectal carcinoma: incidence, risk factors, and radiographic evaluation.
abstract: OBJECTIVE
  Sacral insufficiency fractures after adjuvant radiation for rectal carcinoma can present similarly to recurrent disease. As a complication associated with pelvic radiation, it is important to be aware of the incidence and risk factors associated with sacral fractures in the clinical assessment of these patients.
  
  
  METHODS
  Between 1998 and 2007, a total of 582 patients with locally advanced rectal carcinoma received adjuvant chemoradiation and surgical excision. Of these, 492 patients had imaging studies available for review. Hospital records and imaging studies from all 492 patients were retrospectively evaluated to identify risk factors associated with developing a sacral insufficiency fracture.
  
  
  RESULTS
  With a median follow-up time of 3.5 years, the incidence of sacral fractures was 7.1% (35/492). The 4-year sacral fracture free rate was 0.91. Univariate analysis showed that increasing age (≥60 vs. <60 years), female sex, and history of osteoporosis were significantly associated with shorter time to sacral fracture (P=.01, P=.004, P=.001, respectively). There was no significant difference in the time to sacral fracture for patients based on stage, radiotherapy dose, or chemotherapy regimen. Multivariate analysis showed increasing age (≥60 vs. <60 years, hazard ratio [HR] = 2.50, 95% confidence interval [CI] = 1.22-5.13, P=.01), female sex (HR = 2.64, CI = 1.29-5.38, P=.008), and history of osteoporosis (HR = 3.23, CI = 1.23-8.50, P=.02) were independent risk factors associated with sacral fracture.
  
  
  CONCLUSIONS
  Sacral insufficiency fractures after pelvic radiation for rectal carcinoma occur more commonly than previously described. Independent risk factors associated with fracture were osteoporosis, female sex, and age greater than 60 years.
authors.affiliation: Department of Orthopedic Surgery, Washington University, St. Louis, Missouri.
authors.forename: Han Jo
authors.initials: HJ
authors.lastname: Kim
authors.forename: Patrick J
authors.initials: PJ
authors.lastname: Boland
authors.forename: Dennis S
authors.initials: DS
authors.lastname: Meredith
authors.forename: Eric
authors.initials: E
authors.lastname: Lis
authors.forename: Zhigang
authors.initials: Z
authors.lastname: Zhang
authors.forename: Weiji
authors.initials: W
authors.lastname: Shi
authors.forename: Yoshiya J
authors.initials: YJ
authors.lastname: Yamada
authors.forename: Karyn A
authors.initials: KA
authors.lastname: Goodman
mesh_terms: D000704:Analysis of Variance; D059186:Chemoradiotherapy, Adjuvant / Q000009:adverse effects*; D005260:Female; D006801:Humans; D015994:Incidence; D008297:Male; D008875:Middle Aged; D010024:Osteoporosis / Q000150:complications; D011859:Radiography; D012004:Rectal Neoplasms / Q000628:therapy*; D012189:Retrospective Studies; D012307:Risk Factors; D012447:Sacrum / Q000000981:diagnostic imaging / Q000293:injuries* / Q000528:radiation effects; D016103:Spinal Fractures / Q000000981:diagnostic imaging / Q000453:epidemiology / Q000209:etiology*