title: Free-to-total prostate specific antigen ratio as a single test for detection of significant stage T1c prostate cancer.
abstract: OBJECTIVE
  We investigated whether impalpable, invisible (stage T1c) but significant prostate cancer can be detected better by determining the free-to-total prostate specific antigen (PSA) ratio of equivocal PSA serum levels.
  
  
  METHODS
  The specificity of free-to-total PSA ratio using research monoclonal enzyme immunoassays was compared to that of PSA greater than 4.0 ng./ml. in 117 consecutive patients with PSA 3 to 15 ng./ml. (Hybritech Tandem-R assay) due to untreated benign prostatic hypertrophy or prostate cancer. Of the patients 77% underwent adenectomy or radical prostatectomy with thorough pathological evaluation of surgical specimens.
  
  
  RESULTS
  Benign prostatic hypertrophy had a greater median free-to-total PSA ratio than stages T1c and T2 or greater prostate cancer (0.16 versus 0.09 and 0.11 ng./ml., p = 0.0001 and p = 0.0268, respectively). In stage T1c prostate cancer, areas under receiver operating characteristic curves were 0.58 and 0.84 for PSA and free-to-toal PSA ratio, and free-to-total PSA ratio correlated with prostate volume (r = 0.49, p = 0.005) and Gleason score (r = -0.37, p = 0.036). Pathologically, 84% of stage T1c cancers were significant and comparable to stage T2 or greater cancers.
  
  
  CONCLUSIONS
  Free-to-total PSA ratio enhances the efficacy of PSA measurement by improving specificity for detecting impalpable, invisible but significant stage T1c prostate cancer.
authors.affiliation: Department of Urology, University Hospitals of KU Leuven, Belgium.
authors.forename: A A
authors.initials: AA
authors.lastname: Elgamal
authors.forename: F J
authors.initials: FJ
authors.lastname: Cornillie
authors.forename: H P
authors.initials: HP
authors.lastname: Van Poppel
authors.forename: W M
authors.initials: WM
authors.lastname: Van de Voorde
authors.forename: R
authors.initials: R
authors.lastname: McCabe
authors.forename: L V
authors.initials: LV
authors.lastname: Baert
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D006801:Humans; D008297:Male; D008875:Middle Aged; D009367:Neoplasm Staging; D017430:Prostate-Specific Antigen / Q000097:blood*; D011471:Prostatic Neoplasms / Q000097:blood* / Q000175:diagnosis*; D012372:ROC Curve; D012680:Sensitivity and Specificity
chemical_list: D017430:Prostate-Specific Antigen