title: [Usefulness of the percentage of free prostatic specific antigen in the differential diagnosis between benign prostatic hyperplasia and prostate cancer].
abstract: BACKGROUND
  PSA (prostatic specific antigen) is the most used tumor marker to monitor prostate cancer (PC). It is an acceptably sensitive test. Molecular forms of PSA give a chance to improve its specificity. We have evaluated the usefulness of the ratio free PSA/total PSA (f-PSA/t-PSA%) to diagnose prostate cancer, in the range between 4 and 20 ng/ml; i.e. the interval in which values overlap for patients with PC and benign prostatic hyperplasia (BPH) in our environment.
  
  
  METHODS
  Prospective study on 269 patients, 73 with PC and 196 with BPH. Both t-PSA and f-PSA were determined using microparticles enzyme immune assay (MEIA) with AXSYM (Abbott) analyzer.
  
  
  RESULTS
  Statistically significant differences were evidenced in f-PSA/t-PSA% for patients with PC vs. BPH; but that did not happen for t-PSA values. Sensitivity and specificity values were established for different cut-off points. ROC curve analysis proved diagnostic efficacy was better for f-PSA/t-PSA% than for t-PSA.
  
  
  CONCLUSIONS
  f-PSA/t-PSA percentage is a useful tool for the differential diagnosis between PC and BPH. A ratio lower than 12% selects a population with high risk of cancer. A percentage over 18% is useful to avoid or delay the indication of biopsy.
authors.affiliation: Servicio de Análisis Clínicos. Departamento de Ciencias Morfológicas y Cirugía. Hospital Universitario Príncipe de Asturias. Alcalá de Henares. Madrid. mgaspar@hupa.insalud.es
authors.forename: M J
authors.initials: MJ
authors.lastname: Gaspar
authors.forename: I
authors.initials: I
authors.lastname: Arribas
authors.forename: J M
authors.initials: JM
authors.lastname: Hontoria
authors.forename: P
authors.initials: P
authors.lastname: Bokobo
authors.forename: C
authors.initials: C
authors.lastname: Coca
authors.forename: J C
authors.initials: JC
authors.lastname: Angulo
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D003937:Diagnosis, Differential; D006801:Humans; D007124:Immunoenzyme Techniques; D008297:Male; D008875:Middle Aged; D011446:Prospective Studies; D017430:Prostate-Specific Antigen / Q000097:blood*; D011470:Prostatic Hyperplasia / Q000097:blood* / Q000175:diagnosis; D011471:Prostatic Neoplasms / Q000097:blood* / Q000175:diagnosis
chemical_list: D017430:Prostate-Specific Antigen