title: Competing-risks mortality after radiotherapy vs. observation for localized prostate cancer: a population-based study.
abstract: OBJECTIVE
  Contemporary patients with localized prostate cancer (PCa) are more frequently treated with radiotherapy. However, there are limited data on the effect of this treatment on cancer-specific mortality (CSM). Our objective was to test the relationship between radiotherapy and survival in men with localized PCa and compare it with those treated with observation.
  
  
  METHODS
  A population-based cohort identified 68,797 men with cT1-T2 PCa treated with radiotherapy or observation between the years 1992 and 2005. Propensity-score matching was used to minimize potential bias related to treatment assignment. Competing-risks analyses tested the effect of treatment type (radiotherapy vs. observation) on CSM, after accounting to other-cause mortality. All analyses were carried out within PCa risk, baseline comorbidity status, and age groups.
  
  
  RESULTS
  Radiotherapy was associated with more favorable 10-year CSM rates than observation in patients with high-risk PCa (8.8 vs. 14.4%, hazard ratio [HR]: 0.59, 95% confidence interval [CI]: 0.50-0.68). Conversely, the beneficial effect of radiotherapy on CSM was not evident in patients with low-intermediate risk PCa (3.7 vs. 4.1%, HR: 0.91, 95% CI: 0.80-1.04). Radiotherapy was beneficial in elderly patients (5.6 vs. 7.3%, HR: 0.70, 95% CI: 0.59-0.80). Moreover, it was associated with improved CSM rates among patients with no comorbidities (5.7 vs. 6.5%, HR: 0.81, 95% CI: 0.67-0.98), one comorbidity (4.6 vs. 6.0%, HR: 0.87, 95% CI: 0.75-0.99), and more than two comorbidities (4.2 vs. 5.0%, HR: 0.79, 95% CI: 0.65-0.96).
  
  
  CONCLUSIONS
  Radiotherapy substantially improves CSM in patients with high-risk PCa, with little or no benefit in patients with low-/intermediate-risk PCa relative to observation. These findings must be interpreted within the context of the limitations of observational data.
authors.affiliation: Cancer Prognostics and Health Outcomes Unit, University of Montreal Health Centre, Montreal, Canada. firas.abdollah@gmail.com
authors.forename: Firas
authors.initials: F
authors.lastname: Abdollah
authors.forename: Maxine
authors.initials: M
authors.lastname: Sun
authors.forename: Jan
authors.initials: J
authors.lastname: Schmitges
authors.forename: Rodolphe
authors.initials: R
authors.lastname: Thuret
authors.forename: Zhe
authors.initials: Z
authors.lastname: Tian
authors.forename: Shahrokh F
authors.initials: SF
authors.lastname: Shariat
authors.forename: Alberto
authors.initials: A
authors.lastname: Briganti
authors.forename: Claudio
authors.initials: C
authors.lastname: Jeldres
authors.forename: Paul
authors.initials: P
authors.lastname: Perrotte
authors.forename: Francesco
authors.initials: F
authors.lastname: Montorsi
authors.forename: Pierre I
authors.initials: PI
authors.lastname: Karakiewicz
mesh_terms: D000367:Age Factors; D000368:Aged; D000369:Aged, 80 and over; D002423:Cause of Death; D015897:Comorbidity; D006801:Humans; D008297:Male; D006278:Medicare / Q000706:statistics & numerical data; D060787:Neoplasm Grading; D009367:Neoplasm Staging; D017430:Prostate-Specific Antigen; D011471:Prostatic Neoplasms / Q000401:mortality* / Q000473:pathology / Q000532:radiotherapy*; D011878:Radiotherapy / Q000706:statistics & numerical data; D018570:Risk Assessment; D018426:SEER Program; D012959:Socioeconomic Factors; D014481:United States; D057832:Watchful Waiting / Q000706:statistics & numerical data*
chemical_list: D017430:Prostate-Specific Antigen