title: Obesity is associated with risk of progression for low-risk prostate cancers managed expectantly.
abstract: BACKGROUND
  Active surveillance (AS) is an expectant management strategy for prostate cancer (PCa). The impact of obesity on progression is not well characterized in this population.
  
  
  OBJECTIVE
  To determine if obesity is associated with progression in men on AS for low-risk PCa.
  
  
  METHODS
  Men undergoing AS for low-risk PCa (no Gleason pattern ≥4, three or fewer cores involved or one-third or less of the total number of cores involved, and no core with >50% cancer involvement) were identified at our institution.
  
  
  METHODS
  The outcomes were pathologic progression (defined as no longer meeting low-risk criteria on follow-up biopsy) and therapeutic progression (defined as intent to initiate active treatment). Kaplan-Meier curves and multivariable logistic regression and Cox proportional hazards models were used, with separate models for reclassification at confirmatory biopsy (first biopsy after diagnostic biopsy) and progression beyond confirmatory biopsy.
  
  
  CONCLUSIONS
  In this cohort of 565 men (median follow-up: 48 mo), 124 (22%) were obese (body mass index [BMI] ≥30kg/m(2)). Pathologic and therapeutic progression occurred in 168 men (30%) and 172 men (30%), respectively. No association was noted between obesity and risk of progression at the confirmatory biopsy. However, beyond confirmatory biopsy, obesity was associated with a greater probability of pathologic progression (p=0.007) and therapeutic progression (p=0.007) in Kaplan-Meier analyses. In adjusted Cox models, each 5-unit increase in BMI was associated with an increased risk of pathologic progression (hazard ratio [HR]: 1.5; 95% confidence interval [CI], 1.1-2.1; p=0.02) and therapeutic progression (HR: 1.4; 95% CI, 1.0-1.9; p=0.05). The main limitation is the retrospective design, limiting the ability to assess BMI changes over time.
  
  
  CONCLUSIONS
  Obesity was associated with a significantly increased risk of progression beyond the confirmatory biopsy. This suggests an increased risk of long-term biologic progression rather than solely misclassification.
  
  
  RESULTS
  As opposed to immediate active treatment (surgery or radiation), active surveillance (AS) involves closely monitoring low-risk prostate cancers and only using active treatment if there are signs of progression. Our study is the first to suggest that obesity is associated with a higher risk of cancer progression while on AS. Further research is needed to determine if diet and exercise can decrease the risk of cancer progression while on AS.
authors: Division of Urology, Department of Surgery, University Health Network, University of Toronto, Toronto, Ontario, Canada. Electronic address: bimal.bhindi@mail.utoronto.ca.
authors: Bimal
authors: B
authors: Bhindi
authors: Division of Urology, Department of Surgery, University Health Network, University of Toronto, Toronto, Ontario, Canada; Institute for Clinical and Evaluative Sciences, University of Toronto, Toronto, Ontario, Canada.
authors: Girish S
authors: GS
authors: Kulkarni
authors: Division of Urology, Department of Surgery, University Health Network, University of Toronto, Toronto, Ontario, Canada.
authors: Antonio
authors: A
authors: Finelli
authors: Department of Medicine, University Health Network, University of Toronto, Toronto, Ontario, Canada.
authors: Shabbir M H
authors: SM
authors: Alibhai
authors: Division of Urology, Department of Surgery, University Health Network, University of Toronto, Toronto, Ontario, Canada.
authors: Robert J
authors: RJ
authors: Hamilton
authors: Department of Medical Imaging, University Health Network, University of Toronto, Toronto, Ontario, Canada.
authors: Ants
authors: A
authors: Toi
authors: Department of Pathology, University Health Network, University of Toronto, Toronto, Ontario, Canada.
authors: Theodorus H
authors: TH
authors: van der Kwast
authors: Department of Pathology, University Health Network, University of Toronto, Toronto, Ontario, Canada.
authors: Andrew
authors: A
authors: Evans
authors: Division of Urology, Department of Surgery, University Health Network, University of Toronto, Toronto, Ontario, Canada.
authors: Karen
authors: K
authors: Hersey
authors: Division of Urology, Department of Surgery, University Health Network, University of Toronto, Toronto, Ontario, Canada.
authors: Michael A S
authors: MA
authors: Jewett
authors: Division of Urology, Department of Surgery, University Health Network, University of Toronto, Toronto, Ontario, Canada.
authors: Alexandre R
authors: AR
authors: Zlotta
authors: Division of Urology, Department of Surgery, University Health Network, University of Toronto, Toronto, Ontario, Canada.
authors: John
authors: J
authors: Trachtenberg
authors: Division of Urology, Department of Surgery, University Health Network, University of Toronto, Toronto, Ontario, Canada.
authors: Neil E
authors: NE
authors: Fleshner
mesh_terms: D000368:Aged; D001706:Biopsy; D015992:Body Mass Index; D018450:Disease Progression; D006801:Humans; D053208:Kaplan-Meier Estimate; D008297:Male; D008875:Middle Aged; D015999:Multivariate Analysis; D060787:Neoplasm Grading; D009367:Neoplasm Staging; D009765:Obesity / Q000150:complications* / Q000175:diagnosis; D009864:Ontario; D011237:Predictive Value of Tests; D016016:Proportional Hazards Models; D011471:Prostatic Neoplasms / Q000150:complications / Q000473:pathology / Q000628:therapy*; D012189:Retrospective Studies; D018570:Risk Assessment; D012307:Risk Factors; D013997:Time Factors; D057832:Watchful Waiting
keywords: Active surveillance; Obesity; Prostatic neoplasms; Watchful waiting