title: Severe genitourinary toxicity following radiation therapy for prostate cancer--how long does it last?
abstract: OBJECTIVE
  Radiation therapy is a common treatment for localized prostate cancer but long-term data are sparse on treatment related toxicity compared to observation. We evaluated the time course of grade 2-4 genitourinary toxicities in men treated with primary radiation or observation for T1-T2 prostate cancer.
  
  
  METHODS
  We performed a population based cohort study using Medicare claims data linked to SEER (Surveillance, Epidemiology and End Results) data. Cumulative incidence functions for time to first genitourinary event were calculated based on the competing risks model with death before any genitourinary event as a competing event. The generalized estimating equation method was used to evaluate the risk ratios of recurrent events.
  
  
  RESULTS
  Of the study patients 60,134 received radiation therapy and 25,904 underwent observation. The adjusted risk ratio for genitourinary toxicity was 2.49 (95% CI 2.00-3.11) for 10 years and thereafter. Patients who had required prior procedures for obstruction/stricture, including transurethral prostate resection, before radiation therapy were at significantly increased risk for genitourinary toxicity (risk ratio 2.78, 95% CI 2.56-2.94).
  
  
  CONCLUSIONS
  This study demonstrates that the increased risk of grade 2-4 genitourinary toxicities attributable to radiation therapy persists 10 years after treatment and thereafter. Patients who required prior procedures for obstruction/stricture were at higher risk for genitourinary toxicity than those without these preexisting conditions.
authors.affiliation: The Dean and Betty Gallo Prostate Cancer Center, University of Medicine and Dentistry of New Jersey, Robert Wood Johnson Medical School, New Brunswick, New Jersey 08903, USA.
authors.forename: Sung
authors.initials: S
authors.lastname: Kim
authors.forename: Dirk F
authors.initials: DF
authors.lastname: Moore
authors.forename: Weichung
authors.initials: W
authors.lastname: Shih
authors.forename: Yong
authors.initials: Y
authors.lastname: Lin
authors.forename: Hui
authors.initials: H
authors.lastname: Li
authors.forename: Yu-Hsuan
authors.initials: YH
authors.lastname: Shao
authors.forename: Shunhua
authors.initials: S
authors.lastname: Shen
authors.forename: Grace L
authors.initials: GL
authors.lastname: Lu-Yao
mesh_terms: D000368:Aged; D000369:Aged, 80 and over; D015331:Cohort Studies; D006801:Humans; D008297:Male; D052801:Male Urogenital Diseases / Q000209:etiology*; D011471:Prostatic Neoplasms / Q000532:radiotherapy*; D011832:Radiation Injuries / Q000209:etiology*; D011878:Radiotherapy / Q000009:adverse effects; D012720:Severity of Illness Index; D013997:Time Factors