title: Sacral insufficiency fractures after preoperative chemoradiation for rectal cancer: incidence, risk factors, and clinical course.
abstract: OBJECTIVE
  Sacral insufficiency (SI) fractures can occur as a late side effect of pelvic radiation therapy. Our goal was to determine the incidence, risk factors, and clinical course of SI fractures in patients treated with preoperative chemoradiation for rectal cancer.
  
  
  METHODS
  Between 1989 and 2004, 562 patients with non-metastatic rectal adenocarcinoma were treated with preoperative chemoradiation followed by mesorectal excision. The median radiotherapy dose was 45 Gy. The hospital records and radiology reports of these patients were reviewed to identify those with pelvic fractures. Radiology images of patients with pelvic fractures were then reviewed to identify those with SI fractures.
  
  
  RESULTS
  Among the 562 patients, 15 had SI fractures. The 3-year actuarial rate of SI fractures was 3.1%. The median time to SI fractures was 17 months (range, 2-34 months). The risk of SI fractures was significantly higher in women compared to men (5.8% vs. 1.6%, p = 0.014), and in whites compared with non-whites (4% vs. 0%, p = 0.037). On multivariate analysis, gender independently predicted for the risk of SI fractures (hazard ratio, 3.25; p = 0.031). Documentation about the presence or absence of pain was available for 13 patients; of these 7 (54%) had symptoms requiring pain medications. The median duration of pain was 22 months. No patient required hospitalization or invasive intervention for pain control.
  
  
  CONCLUSIONS
  SI fractures were uncommon in patients treated with preoperative chemoradiation for rectal cancer. The risk of SI fractures was significantly higher in women. Most cases of SI fractures can be managed conservatively with pain medications.
authors.affiliation: Department of Radiation Oncology, UT MD Anderson Cancer Center, Houston, TX 77030, USA.
authors.forename: Michael P
authors.initials: MP
authors.lastname: Herman
authors.forename: Scott
authors.initials: S
authors.lastname: Kopetz
authors.forename: Priya R
authors.initials: PR
authors.lastname: Bhosale
authors.forename: Cathy
authors.initials: C
authors.lastname: Eng
authors.forename: John M
authors.initials: JM
authors.lastname: Skibber
authors.forename: Miguel A
authors.initials: MA
authors.lastname: Rodriguez-Bigas
authors.forename: Barry W
authors.initials: BW
authors.lastname: Feig
authors.forename: George J
authors.initials: GJ
authors.lastname: Chang
authors.forename: Marc E
authors.initials: ME
authors.lastname: Delclos
authors.forename: Sunil
authors.initials: S
authors.lastname: Krishnan
authors.forename: Christopher H
authors.initials: CH
authors.lastname: Crane
authors.forename: Prajnan
authors.initials: P
authors.lastname: Das
mesh_terms: D000230:Adenocarcinoma / Q000188:drug therapy* / Q000532:radiotherapy* / Q000601:surgery; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D003131:Combined Modality Therapy / Q000379:methods; D005260:Female; D006801:Humans; D015994:Incidence; D008297:Male; D008875:Middle Aged; D015999:Multivariate Analysis; D010146:Pain / Q000188:drug therapy / Q000209:etiology; D011879:Radiotherapy Dosage; D012004:Rectal Neoplasms / Q000188:drug therapy* / Q000532:radiotherapy* / Q000601:surgery; D012307:Risk Factors; D012447:Sacrum / Q000293:injuries* / Q000528:radiation effects; D012737:Sex Factors; D016103:Spinal Fractures / Q000188:drug therapy / Q000453:epidemiology / Q000209:etiology*; D055815:Young Adult