title: Serum pro prostate specific antigen improves cancer detection compared to free and complexed prostate specific antigen in men with prostate specific antigen 2 to 4 ng/ml.
abstract: OBJECTIVE
  Pro prostate specific antigen (pPSA) is a precursor form of PSA enriched in tumor compared to benign prostate tissues that may be a more specific serum marker for prostate cancer. Serum pPSA was measured in the clinically relevant early detection PSA range of 2 to 10 ng/ml.
  
  
  METHODS
  Research use immunoassays were used to measure native and truncated forms of pPSA. The subject cohort contained 1,091 serum specimens from men enrolled in prostate cancer screening studies at 2 sites who had undergone prostate biopsy and were divided into PSA ranges of 2 to 4 ng/ml (benign 320, cancer 235) and 4 to 10 ng/ml (benign 315, cancer 221).
  
  
  RESULTS
  In PSA ranges 2 to 4, 2 to 6, 4 to 10 and 2 to 10 ng/ml, pPSA in a ratio with free PSA (%pPSA) gave the highest cancer specificity. At 2 to 4 ng/ml and 90% sensitivity, %pPSA spared 19% of unnecessary biopsies compared to 10% for free PSA and 11% for complexed PSA(p <0.001). Similar results were obtained at PSA 2 to 6 ng/ml. At 90% sensitivity in the PSA 4 to 10 ng/ml range, %pPSA spared 31% of unnecessary biopsies compared to 20% for % free PSA and 19% for complexed PSA (p <0.0001). In the combined 2 to 10 ng/ml range, %pPSA spared 21% of unnecessary biopsies compared to 13% for % free PSA and 9% for complexed PSA (p <0.0001).
  
  
  CONCLUSIONS
  The %pPSA significantly improved specificity for cancer detection and decreased the number of unnecessary biopsies in the PSA 2 to 4 ng/ml range. This relative improvement of %pPSA compared to % free PSA and complexed PSA was maintained throughout the PSA range of 2 to 10 ng/ml.
authors.affiliation: Washington University, St. Louis, Missouri, USA.
authors.forename: William J
authors.initials: WJ
authors.lastname: Catalona
authors.forename: Georg
authors.initials: G
authors.lastname: Bartsch
authors.forename: Harry G
authors.initials: HG
authors.lastname: Rittenhouse
authors.forename: Cindy L
authors.initials: CL
authors.lastname: Evans
authors.forename: Harry J
authors.initials: HJ
authors.lastname: Linton
authors.forename: Anna
authors.initials: A
authors.lastname: Amirkhan
authors.forename: Wolfgang
authors.initials: W
authors.lastname: Horninger
authors.forename: Helmut
authors.initials: H
authors.lastname: Klocker
authors.forename: Stephen D
authors.initials: SD
authors.lastname: Mikolajczyk
mesh_terms: D001707:Biopsy, Needle; D006801:Humans; D008297:Male; D017430:Prostate-Specific Antigen / Q000097:blood*; D011471:Prostatic Neoplasms / Q000175:diagnosis* / Q000473:pathology; D011498:Protein Precursors / Q000097:blood*; D012372:ROC Curve; D011863:Radioimmunoassay; D012189:Retrospective Studies; D012680:Sensitivity and Specificity
chemical_list: D011498:Protein Precursors; D017430:Prostate-Specific Antigen