title: Can percent free prostate-specific antigen reduce the need for prostate biopsy?
abstract: BACKGROUND
  In a recent multicenter study, percent free prostate-specific antigen (PSA) enhanced the specificity of PSA testing in prostate cancer screening.
  
  
  OBJECTIVE
  To determine whether the percent free PSA could be as effective in reducing the need for biopsy in a managed care setting as in an academic setting.
  
  
  METHODS
  Kaiser Permanente Northwest Region (Portland, Oregon) and Kaiser Permanente Oakland/Berkeley (California).
  
  
  METHODS
  Prospective blinded study conducted by using Hybritech Tandem PSA and Hybritech Tandem free PSA assays (Beckman Coulter, Inc., Fullerton, California).
  
  
  METHODS
  250 men (63 with prostate cancer and 187 with benign prostate conditions) who were older than 40 years of age, had a PSA level of 4.0 to 10.0 ng/mL, and had a histologically confirmed diagnosis.
  
  
  METHODS
  Sensitivity and specificity of percent free PSA.
  
  
  RESULTS
  The median percent free PSA values for patients with cancer (free PSA, 13%) significantly differed from that for patients without cancer (free PSA, 17%) (P = 0.001). When a free PSA cutoff of 25% was used, the sensitivity was 97% (95% CI, 92% to 100%) and the specificity was 13% (CI, 8% to 18%). These results were not significantly different from those obtained in the multicenter study (95% sensitivity, 20% specificity for a free PSA cutoff of 25%).
  
  
  CONCLUSIONS
  The results obtained in a managed care organization were similar to those obtained at large university medical centers and show that the percent free PSA can be used to enhance the specificity of PSA testing for prostate cancer.
authors.affiliation: Kaiser Permanente Northwest Region, Clackamas, OR, USA. LIEBERMANST@kpnwoa.mts.kpnw.org
authors.forename: S
authors.initials: S
authors.lastname: Lieberman
mesh_terms: D000368:Aged; D001706:Biopsy; D006801:Humans; D008297:Male; D008875:Middle Aged; D011237:Predictive Value of Tests; D011446:Prospective Studies; D017430:Prostate-Specific Antigen / Q000097:blood*; D011469:Prostatic Diseases / Q000097:blood; D011471:Prostatic Neoplasms / Q000097:blood* / Q000175:diagnosis; D012680:Sensitivity and Specificity; D016037:Single-Blind Method; D018709:Statistics, Nonparametric
chemical_list: D017430:Prostate-Specific Antigen