title: Bladder dose-volume parameters are associated with urinary incontinence after postoperative intensity modulated radiation therapy for prostate cancer.
abstract: OBJECTIVE
  Urinary incontinence is a potential side effect of prostatectomy and intensity modulated radiation therapy (IMRT) for prostate cancer. There are limited data on dosimetric parameters that may predict for poor continence recovery in men who receive postoperative IMRT.
  
  
  METHODS
  Eighty-seven men with nonmetastatic prostate cancer who underwent prostatectomy followed by adjuvant (13%) or salvage (87%) IMRT were identified. The Expanded Prostate Cancer Index composite questionnaire was prospectively collected at baseline, 6 weeks, and 6, 12, 18, 24, 36, and 48 months post-IMRT. Relevant critical structures were contoured and dose-volume metrics collected. The primary endpoint was urinary continence global score. Longitudinal analysis using a generalized estimating equation model was performed.
  
  
  RESULTS
  There was no statistically significant change in Expanded Prostate Cancer Index composite urinary continence global scores over time as compared with baseline (all P > .05). In univariate analysis, bladder volume receiving 70 Gy (V70 Gy) and penile bulb V70 Gy were associated with urinary continence (odds ratio, 0.82; P < .05). In a multivariable model that included body mass index, distance between vesicourethral junction and genitourinary diaphragm, time from surgery, use of antihypertensive medications, age, diabetes, and bladder V70 Gy, only bladder V70 Gy (odds ratio, 0.82; P = .03) was associated with outcome. After 2 years, there was a significant difference in global score for those with V70 Gy < 42.27 versus ≥42.27 mL (all P < .05 at 2 and 3 years post-IMRT).
  
  
  CONCLUSIONS
  There was no significant change in patient-reported urinary continence scores after postprostatectomy IMRT. Bladder V70 Gy was independently associated with a decrease in urinary continence scores. Further evaluation is necessary to optimize quality of life in these men.
authors.affiliation: Department of Radiation and Cellular Oncology, University of Chicago, Chicago, Illinois.
authors.forename: Christina H
authors.initials: CH
authors.lastname: Son
authors.affiliation: Department of Radiation and Cellular Oncology, University of Chicago, Chicago, Illinois.
authors.forename: James M
authors.initials: JM
authors.lastname: Melotek
authors.affiliation: Department of Public Health Sciences, University of Chicago, Chicago, Illinois.
authors.forename: Chuanhong
authors.initials: C
authors.lastname: Liao
authors.affiliation: Department of Radiation and Cellular Oncology, University of Chicago, Chicago, Illinois.
authors.forename: Greg
authors.initials: G
authors.lastname: Hubert
authors.affiliation: Department of Radiation and Cellular Oncology, University of Chicago, Chicago, Illinois.
authors.forename: Charles A
authors.initials: CA
authors.lastname: Pelizzari
authors.affiliation: Department of Urology, University of Chicago, Chicago, Illinois.
authors.forename: Scott E
authors.initials: SE
authors.lastname: Eggener
authors.affiliation: Department of Radiation and Cellular Oncology, University of Chicago, Chicago, Illinois. Electronic address: sliauw@radonc.uchicago.edu.
authors.forename: Stanley L
authors.initials: SL
authors.lastname: Liauw
mesh_terms: D006801:Humans; D008297:Male; D008875:Middle Aged; D011184:Postoperative Period; D011446:Prospective Studies; D011471:Prostatic Neoplasms / Q000150:complications* / Q000473:pathology; D050397:Radiotherapy, Intensity-Modulated / Q000379:methods*; D011795:Surveys and Questionnaires; D001743:Urinary Bladder / Q000473:pathology*; D014549:Urinary Incontinence / Q000209:etiology*