title: Urethral strictures following high-dose-rate brachytherapy for prostate cancer: analysis of risk factors.
abstract: OBJECTIVE
  High-dose-rate brachytherapy is an established technique to deliver a conformal dose of radiation to patients with prostate cancer. The William Buckland Radiotherapy Center has been performing high-dose-rate brachytherapy with external beam radiation treatment for prostate cancer since 1998 and has an extensive prospective database on all patients treated. The purpose of this analysis was to assess the risk of stricture formation and identify the predictive or causative factors.
  
  
  METHODS
  Three hundred fifty-four patients were treated between 1998 and 2008. Patients received one of three differing dose schedules: 20Gy in four treatments (20Gy/4), 18Gy/3, and 19Gy/2 during three sequential time periods. Nelson-Aalen cumulative hazard modeling was used to estimate risk of events over time. Potential risk factors, including dose, were identified and used in the analysis.
  
  
  RESULTS
  There were 45 patients who developed at least one stricture, an overall risk of 8.2% at 2 years. The 2-year risk of stricture formation was 3.4%, 2.3%, and 31.6% for 18Gy/3, 20Gy/4, and 19Gy/2, respectively. Most strictures occurred in the bulbomembranous urethra (50%) or external sphincter region (33%). On multivariable analysis, the dose schedule used was the only significant predictor for increased stricture formation.
  
  
  CONCLUSIONS
  In our patients, those who received 19Gy/2 were at a significantly higher risk of stricture formation. Most of these strictures were mild, requiring only one intervention but a 2-year stricture risk of 31.6% was striking, and we have modified our protocol.
authors.affiliation: William Buckland Radiation Oncology, Alfred Health, Melbourne, Victoria, Australia. Ben.hindson@wbrc.org.au
authors.forename: Benjamin R
authors.initials: BR
authors.lastname: Hindson
authors.forename: Jeremy L
authors.initials: JL
authors.lastname: Millar
authors.forename: Bronwyn
authors.initials: B
authors.lastname: Matheson
mesh_terms: D000368:Aged; D000369:Aged, 80 and over; D001918:Brachytherapy / Q000706:statistics & numerical data*; D015897:Comorbidity; D006801:Humans; D015994:Incidence; D008297:Male; D008875:Middle Aged; D011471:Prostatic Neoplasms / Q000453:epidemiology* / Q000532:radiotherapy*; D011832:Radiation Injuries / Q000453:epidemiology*; D011878:Radiotherapy; D018570:Risk Assessment; D016896:Treatment Outcome; D014525:Urethral Stricture / Q000453:epidemiology*; D014739:Victoria / Q000453:epidemiology