title: Percentage of free prostate-specific antigen: implications in modern extended scheme prostate biopsy.
abstract: OBJECTIVE
  To validate the performance of percentage of free prostate-specific antigen (%fPSA) in men undergoing extended scheme biopsy. The current cutoff values for %fPSA were chosen using data from sextant biopsies, which have been known to miss a significant number of prostate cancer cases. Additionally, we sought to validate the use of %fPSA in men with a total PSA < 4.0 ng/mL or > 10.0 ng/mL.
  
  
  METHODS
  We evaluated %fPSA performance in 1077 men who had undergone initial extended prostate biopsy. The men were categorized according to their PSA level into 2 groups (>4.0 and ≤4.0) ng/mL.
  
  
  RESULTS
  The overall cancer detection rate was 42.1%. The mean PSA level was 7.6 ng/mL, and the mean %fPSA was 18.0%. The area under the curve for %fPSA was 0.59 (95% confidence interval 0.57-0.61) for all PSA levels, comparable to previous reports from sextant biopsy series. The performance of %fPSA in predicting prostate cancer on initial extended biopsy was improved with a PSA level of ≤4.0 ng/mL (area under the curve 0.66, 95% confidence interval 0.62-0.70) compared with a PSA level >4.0 ng/mL (area under the curve 0.57, 95% confidence interval 0.55-0.59; P < .001). A specificity of 85% was achieved for a %fPSA cutoff of 11% for the ≤4.0-ng/mL group and 10% for the >4.0-ng/mL group.
  
  
  CONCLUSIONS
  The performance of %fPSA in predicting the presence of prostate cancer was not altered when an extended biopsy scheme was used. Although a %fPSA level greater than our cutoffs would not rule out prostate cancer, a low %fPSA would be particularly useful in predicting prostate cancer, especially in men with normal digital rectal examination findings and a PSA level <4 ng/mL.
authors.affiliation: Glickman Urological and Kidney Institute, Cleveland Clinic, Cleveland, OH 44195, USA.
authors.forename: Byron H
authors.initials: BH
authors.lastname: Lee
authors.forename: Ayman S
authors.initials: AS
authors.lastname: Moussa
authors.forename: Jianbo
authors.initials: J
authors.lastname: Li
authors.forename: Khaled
authors.initials: K
authors.lastname: Fareed
authors.forename: J Stephen
authors.initials: JS
authors.lastname: Jones
mesh_terms: D000368:Aged; D019540:Area Under Curve; D001707:Biopsy, Needle / Q000379:methods; D006801:Humans; D016015:Logistic Models; D008297:Male; D008875:Middle Aged; D015999:Multivariate Analysis; D011237:Predictive Value of Tests; D017430:Prostate-Specific Antigen / Q000097:blood*; D011471:Prostatic Neoplasms / Q000175:diagnosis* / Q000473:pathology; D012372:ROC Curve; D012189:Retrospective Studies
chemical_list: D017430:Prostate-Specific Antigen