title: The use of percent free prostate specific antigen for staging clinically localized prostate cancer.
abstract: OBJECTIVE
  The free-to-total serum prostate specific antigen (PSA) ratio (percent free PSA) has been demonstrated to have clinical use for early detection of men with prostate cancer with total PSA levels between 4.0 and 10.0 ng./ml. Several studies evaluating the usefulness of percent free PSA for the staging of clinically localized prostate cancer have provided conflicting results. We further investigate the usefulness of percent free PSA for staging of clinically localized prostate cancer.
  
  
  METHODS
  In 263 men with clinically localized prostate cancer who underwent radical prostatectomy total PSA and free PSA were measured preoperatively. Pathological stages were classified as organ confined in 134 cases, capsular penetration in 92, seminal vesicle involvement in 7, involvement of the surgical margins in 20 and lymph node involvement in 10.
  
  
  RESULTS
  Percent free PSA was significantly different between men with organ confined versus nonorgan confined tumors (p <0.0001) and between those with favorable versus unfavorable pathology (p <0.0001). A cutoff of 12% free PSA provided a 72% positive predictive value and 52% negative predictive value for favorable pathology. A cutoff of 15% free PSA provided a 76% and 53% positive and negative predictive value, respectively, for organ confined disease.
  
  
  CONCLUSIONS
  These data demonstrate that the use of percent free PSA may be of additional value for the staging of clinically localized prostate cancer. The recommendations for cutoff levels of percent free PSA for detection and staging of localized prostate cancer are preliminary and can only be given for this particular assay. A large multicenter trial, controlling for age, stage and grade distribution, as well as for a uniform pathological evaluation and comparable total and free PSA assays, is required to elucidate this issue further.
authors.affiliation: James Buchanan Brady Urological Institute, Department of Pathology, The Johns Hopkins Medical Institution, Baltimore, Maryland, USA.
authors.forename: J
authors.initials: J
authors.lastname: Pannek
authors.forename: H G
authors.initials: HG
authors.lastname: Rittenhouse
authors.forename: D W
authors.initials: DW
authors.lastname: Chan
authors.forename: J I
authors.initials: JI
authors.lastname: Epstein
authors.forename: P C
authors.initials: PC
authors.lastname: Walsh
authors.forename: A W
authors.initials: AW
authors.lastname: Partin
mesh_terms: D000368:Aged; D006801:Humans; D008297:Male; D008875:Middle Aged; D009367:Neoplasm Staging; D011237:Predictive Value of Tests; D017430:Prostate-Specific Antigen / Q000097:blood*; D011471:Prostatic Neoplasms / Q000097:blood* / Q000473:pathology*; D012680:Sensitivity and Specificity
chemical_list: D017430:Prostate-Specific Antigen