title: Influence of dose on risk of acute urinary retention after iodine-125 prostate brachytherapy.
abstract: OBJECTIVE
  To assess the influence of dose on the risk of acute urinary retention (AUR) after iodine-125 prostate brachytherapy.
  
  
  METHODS
  Between January 2005 and December 2008, 714 consecutive patients with localized prostate cancer were treated with iodine-125 prostate brachytherapy at our department. All patients completed four imaging studies: magnetic resonance imaging before and 4 weeks after treatment and intraoperative three-dimensional transrectal ultrasonography before and after implantation. The development of AUR was prospectively recorded. The evaluated treatment and dosimetric parameters included prostate volume, number of needles and seeds used, intra- and postoperative prostate edema, percentage of prostate volume receiving 100%, 150%, and 200% of the prescribed dose to the prostate, minimal dose received by 90% of the prostate volume, and percentage of the urethra receiving 100%, 150%, and 200% of the prescribed dose. Logistic regression analysis was used to examine which factors were associated with AUR.
  
  
  RESULTS
  Of the 714 patients, 57 (8.0%) developed AUR. On univariate analysis, the following treatment and dosimetric factors were significantly associated with AUR: International Prostate Symptom Score (odds ratio [OR], 2.07, per 10-point increase), preimplant prostate volume (OR, 1.06), postimplant prostate volume (OR, 1.04), number of needles used (OR, 1.09), and number of seeds used (OR, 1.03). On multivariate analysis, the only independent predictive factors for AUR were pretreatment prostate volume (OR, 1.05) and International Prostate Symptom Score (OR, 1.76, per 10-point increase). Patients with a pretreatment prostate volume >35 cm(3) had a 10.4% risk of developing AUR compared with 5.4% for those with a prostate volume of ≤ 35 cm(3). No association was found between any of the dosimetric parameters and the development of AUR.
  
  
  CONCLUSIONS
  The radiation dose, within the range studied, did not influence the risk of AUR after iodine-125 prostate brachytherapy. Prostate volume and International Prostate Symptom Score were the most important predictors of AUR.
authors.affiliation: Department of Radiation Oncology, University Medical Center Utrecht, Utrecht, The Netherlands.
authors.forename: Ellen M A
authors.initials: EM
authors.lastname: Roeloffzen
authors.forename: Jan J
authors.initials: JJ
authors.lastname: Battermann
authors.forename: Marijke J H
authors.initials: MJ
authors.lastname: van Deursen
authors.forename: Evelyn M
authors.initials: EM
authors.lastname: Monninkhof
authors.forename: Mareije I
authors.initials: MI
authors.lastname: Visscher
authors.forename: Marinus A
authors.initials: MA
authors.lastname: Moerland
authors.forename: Marco
authors.initials: M
authors.lastname: van Vulpen
mesh_terms: D000208:Acute Disease; D000368:Aged; D000704:Analysis of Variance; D001918:Brachytherapy / Q000009:adverse effects* / Q000295:instrumentation / Q000379:methods; D006801:Humans; D007457:Iodine Radioisotopes / Q000627:therapeutic use; D008279:Magnetic Resonance Imaging; D008297:Male; D009929:Organ Size; D011446:Prospective Studies; D011467:Prostate / Q000473:pathology; D017430:Prostate-Specific Antigen / Q000097:blood; D011471:Prostatic Neoplasms / Q000097:blood / Q000000981:diagnostic imaging / Q000473:pathology / Q000532:radiotherapy*; D011879:Radiotherapy Dosage; D012044:Regression Analysis; D012307:Risk Factors; D047368:Tumor Burden; D014463:Ultrasonography; D016055:Urinary Retention / Q000209:etiology*
chemical_list: D007457:Iodine Radioisotopes; D017430:Prostate-Specific Antigen