title: Electrophoretic subforms of free prostate-specific antigen in serum as promising diagnostic tool in prostate cancer diagnostics.
abstract: OBJECTIVE
  To assess the diagnostic performance of the major electrophoretic subforms of free prostate-specific antigen (PSA), named F2 and F3, for differentiating between benign and malignant prostatic disease in men with total PSA (tPSA) concentrations up to 10 microg/L.
  
  
  METHODS
  In sera from 50 patients with prostate cancer (PCa) and 44 men without evidence of malignancy (NPCa), F2 and F3 were quantified by two-dimensional electrophoresis and Western blotting. The F2/F3 ratios were compared with the conventional parameter tPSA and percentage fPSA/tPSA ratio (%fPSA) in univariate and multivariate analyses using receiver operating characteristic analysis.
  
  
  RESULTS
  F2 was lower in the NPCa group (median 17%) than in the PCa group (55%), and F3 was greater in the NPCa group (62%) than in the PCa group (45%), resulting in a significantly lower F2/F3 ratio in the NPCa group than in the PCa group (0.32 versus 1.21). The F2/F3 ratio correlated with the %fPSA and prostate volume but not Gleason score, tumor stage, age, or tPSA. The F2/F3 ratio and F2-F3/%fPSA ratio had greater areas under the receiver operating characteristic curves than did tPSA or %fPSA, especially in the subgroup of %fPSA greater than 15%. Models of binary logistic regression confirmed the improvement of diagnostic accuracy using the F2/F3 ratio as an independent variable.
  
  
  CONCLUSIONS
  Compared with tPSA and %fPSA, the fPSA subforms F2 and F3, assessed as F2/F3 or F2-F3/%fPSA ratios, enhanced the differentiation between men with and without PCa for tPSA levels up to 10 microg/L. Additional characterization of these forms should be performed to develop a feasible assay.
authors.affiliation: Department of Urology, University Hospital Charité, University Medicine Berlin, Berlin, Germany. klaus.jung@charite.de
authors.forename: Klaus
authors.initials: K
authors.lastname: Jung
authors.forename: Wolfgang
authors.initials: W
authors.lastname: Hoesel
authors.forename: Jeanett
authors.initials: J
authors.lastname: Reiche
authors.forename: Serdar
authors.initials: S
authors.lastname: Deger
authors.forename: Jürgen
authors.initials: J
authors.lastname: Kramer
authors.forename: Stefan A
authors.initials: SA
authors.lastname: Loening
authors.forename: Michael
authors.initials: M
authors.lastname: Lein
authors.forename: Carsten
authors.initials: C
authors.lastname: Stephan
mesh_terms: D000368:Aged; D000369:Aged, 80 and over; D014408:Biomarkers, Tumor / Q000097:blood; D001707:Biopsy, Needle; D016022:Case-Control Studies; D015180:Electrophoresis, Gel, Two-Dimensional; D006801:Humans; D008297:Male; D015999:Multivariate Analysis; D009367:Neoplasm Staging; D011300:Preoperative Care; D011336:Probability; D011379:Prognosis; D017430:Prostate-Specific Antigen / Q000097:blood*; D011468:Prostatectomy / Q000379:methods; D011471:Prostatic Neoplasms / Q000097:blood* / Q000175:diagnosis* / Q000601:surgery; D012372:ROC Curve; D012494:Sampling Studies; D012680:Sensitivity and Specificity; D018709:Statistics, Nonparametric; D000514:alpha 1-Antichymotrypsin / Q000097:blood*
chemical_list: D014408:Biomarkers, Tumor; D000514:alpha 1-Antichymotrypsin; D017430:Prostate-Specific Antigen