title: Association of free-prostate specific antigen subfractions and human glandular kallikrein 2 with volume of benign and malignant prostatic tissue.
abstract: BACKGROUND
  We investigated the association of different subfractions of prostate specific antigen (PSA) and human glandular kallikrein 2 (hK2), such as total PSA (tPSA), complexed PSA (cPSA), free PSA (fPSA), "single-chain Intact fPSA" (fPSA-I), "multi-chain nicked fPSA" (fPSA-N), and total hK2 with volumes of total prostate gland, transition zone (tz), and prostate cancer (PCa) tissue in patients with benign and malignant prostatic disease.
  
  
  METHODS
  Serum samples were collected from men with negative biopsy (n=164) and PCa (n=252). Total and fPSA were measured using a commercially immunoassay. We measured hK2 and fPSA-I by previously reported in-house research assays specific for hK2 and single-chain, non-cleaved fPSA, respectively. Levels of fPSA-N (=fPSA-fPSA-I) and cPSA (=tPSA-fPSA) were calculated. Total prostate and tz volume were measured using transrectal ultrasound (TRUS); PCa volume was calculated using a computer assisted volumetric program. Association with tz and cancer volumes (CaVols) was performed by linear regression analysis.
  
  
  RESULTS
  All PSA subfractions and hK2 were associated with tz volume in multivariable linear regression analysis. Only hK2, fPSA, and fPSA-N were significantly associated with CaVol in multivariable analysis, fPSA-I seemed to be cancer related.
  
  
  CONCLUSIONS
  The multi-chain fPSA-N subfractions of fPSA may be a valuable predictor of both benign prostate hyperplasia (BPH) and CaVol that is likely to be more useful in predicting tz volumes than CaVols. fPSA-I may provide information on cancer without being influenced by the presence of BPH.
authors.affiliation: Department of Urology, University of Hamburg Eppendorf, Hamburg, Germany. steuber@uke.uni-hamburg.de
authors.forename: Thomas
authors.initials: T
authors.lastname: Steuber
authors.forename: Pauliina
authors.initials: P
authors.lastname: Niemela
authors.forename: Alexander
authors.initials: A
authors.lastname: Haese
authors.forename: Kim
authors.initials: K
authors.lastname: Pettersson
authors.forename: Andreas
authors.initials: A
authors.lastname: Erbersdobler
authors.forename: K-H
authors.initials: KH
authors.lastname: Felix Chun
authors.forename: Markus
authors.initials: M
authors.lastname: Graefen
authors.forename: Michael W
authors.initials: MW
authors.lastname: Kattan
authors.forename: Hartwig
authors.initials: H
authors.lastname: Huland
authors.forename: Hans
authors.initials: H
authors.lastname: Lilja
mesh_terms: D000368:Aged; D015415:Biomarkers; D001706:Biopsy; D003937:Diagnosis, Differential; D006801:Humans; D008297:Male; D008875:Middle Aged; D011237:Predictive Value of Tests; D017430:Prostate-Specific Antigen / Q000097:blood*; D011470:Prostatic Hyperplasia / Q000097:blood / Q000473:pathology*; D011471:Prostatic Neoplasms / Q000097:blood / Q000473:pathology*; D020840:Tissue Kallikreins / Q000097:blood*
chemical_list: D015415:Biomarkers; D020840:Tissue Kallikreins; D017430:Prostate-Specific Antigen