title: The prostate cancer risk calculator from the Prostate Cancer Prevention Trial underestimates the risk of high grade cancer in contemporary referral patients.
abstract: OBJECTIVE
  The prostate cancer risk calculator from the Prostate Cancer Prevention Trial estimates the risk of positive biopsy and 1 containing high grade disease (Gleason score 7 or greater) based on prostate specific antigen, digital rectal examination, family history, race and prior negative biopsy. Since data used to create the calculator came from an unreferred population that underwent mainly sextant biopsy, to our knowledge its usefulness in the contemporary urology practice is unknown.
  
  
  METHODS
  We performed the same multivariate logistic regression used to derive the prostate cancer risk calculator in a cohort of men from the Stanford Prostate Needle Biopsy Database who underwent initial prostate needle biopsy using an extended 12-core scheme.
  
  
  RESULTS
  Our predictions of overall prostate cancer risk did not differ significantly from those of the calculator. Prostate specific antigen, abnormal digital rectal examination and family history were independent risk factors. However, our model predicted a much greater risk of high grade disease than the prostate cancer risk calculator. Prostate specific antigen, abnormal digital rectal examination and age were independent risk factors for high grade disease.
  
  
  CONCLUSIONS
  The difference between our estimated risk of high grade prostate cancer and that of the prostate cancer risk calculator can be potentially explained by 1) differences between the cohorts (referred vs unreferred) or 2) the difference in grading, ie grading accuracy due to the difference in biopsy schemes or to temporally related grade shifts. Caution should be used when applying the prostate cancer risk calculator to counsel patients referred for suspicion of prostate cancer since it underestimates the risk of high grade disease.
authors.affiliation: Department of Urology, Stanford University School of Medicine, Stanford, California 94305, USA. tin.ngo@stanford.edu
authors.forename: Tin C
authors.initials: TC
authors.lastname: Ngo
authors.forename: Brit B
authors.initials: BB
authors.lastname: Turnbull
authors.forename: Philip W
authors.initials: PW
authors.lastname: Lavori
authors.forename: Joseph C
authors.initials: JC
authors.lastname: Presti
mesh_terms: D000328:Adult; D017677:Age Distribution; D000368:Aged; D014408:Biomarkers, Tumor / Q000097:blood; D001707:Biopsy, Needle; D002140:California; D015331:Cohort Studies; D051517:Digital Rectal Examination / Q000379:methods; D006801:Humans; D015994:Incidence; D016015:Logistic Models; D008297:Male; D008403:Mass Screening; D008875:Middle Aged; D015999:Multivariate Analysis; D009367:Neoplasm Staging; D049451:Nomograms; D016017:Odds Ratio; D011237:Predictive Value of Tests; D011379:Prognosis; D016016:Proportional Hazards Models; D017430:Prostate-Specific Antigen / Q000097:blood*; D011471:Prostatic Neoplasms / Q000175:diagnosis* / Q000453:epidemiology / Q000517:prevention & control*; D012017:Referral and Consultation / Q000706:statistics & numerical data*; D018570:Risk Assessment
chemical_list: D014408:Biomarkers, Tumor; D017430:Prostate-Specific Antigen