title: Making sense of prostate specific antigen: improving its predictive value in patients undergoing prostate biopsy.
abstract: OBJECTIVE
  The clinical usefulness of PSA for prostate cancer screening is unclear, although the test remains in common use. New methods to interpret PSA are needed.
  
  
  METHODS
  We examined a cohort of 2,637 men who underwent prostate biopsies for abnormal DRE or PSA between 1999 and 2004. Using risk factors for prostate cancer, including patient age, ethnicity, family history of prostate cancer, previous negative biopsy, voiding symptoms and prostate volume, we developed risk groups for prostate cancer using recursive partitioning modeling independent of PSA or DRE. We then compared prostate cancer probabilities by PSA ranges by risk group.
  
  
  RESULTS
  Of the 2,637 men 1,282 (48.6%) had prostate cancer. Age, ethnicity, family history, previous negative biopsy and prostate volume were predictive for cancer. We constructed 6 risk groups by combining these factors and created tables to assign patients to these groups. Independent of PSA and DRE the probability of cancer ranged from 15% in patients in group 1 to 78% in patients in group 6 (p <0.0001). By adding PSA and DRE to each risk group prostate cancer probabilities were refined from 0% to 100%. Patients in the higher risk groups also had higher grade cancer (p <0.0001).
  
  
  CONCLUSIONS
  We generated 6 risk groups based on simple risk factors for prostate cancer. When used in the right context and patient, PSA is highly accurate for predicting prostate cancer and permitting rational decision making in patients with abnormal PSA.
authors.affiliation: Division of Urology, Sunnybrook and Women's College Health Sciences Centre, University of Toronto, Toronto, Ontario, Canada. robert.nam@utoronto.ca
authors.forename: Robert K
authors.initials: RK
authors.lastname: Nam
authors.forename: Ants
authors.initials: A
authors.lastname: Toi
authors.forename: John
authors.initials: J
authors.lastname: Trachtenberg
authors.forename: Laurence H
authors.initials: LH
authors.lastname: Klotz
authors.forename: Michael A S
authors.initials: MA
authors.lastname: Jewett
authors.forename: Marjan
authors.initials: M
authors.lastname: Emami
authors.forename: Linda
authors.initials: L
authors.lastname: Sugar
authors.forename: Joan
authors.initials: J
authors.lastname: Sweet
authors.forename: Greg R
authors.initials: GR
authors.lastname: Pond
authors.forename: Steven A
authors.initials: SA
authors.lastname: Narod
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D001706:Biopsy; D051517:Digital Rectal Examination; D006801:Humans; D008297:Male; D008875:Middle Aged; D011237:Predictive Value of Tests; D017430:Prostate-Specific Antigen / Q000097:blood*; D011471:Prostatic Neoplasms / Q000097:blood* / Q000145:classification / Q000473:pathology*; D012307:Risk Factors
chemical_list: D017430:Prostate-Specific Antigen