title: The influence of prostate volume on the ratio of free to total prostate specific antigen in serum of patients with prostate carcinoma and benign prostate hyperplasia.
abstract: BACKGROUND
  Determining the ratio of free to total prostate specific antigen (f-PSA to t-PSA, calculated as the percentage of f-PSA [f-PSA%]) in serum allow for a clearer distinction between patients with prostate carcinoma (PCa) and patients with benign prostate hyperplasia (BPH) than determining the level of t-PSA alone. To find influencing factors on f-PSA%, the authors investigated prostate volume, TNM classification, and tumor stage.
  
  
  METHODS
  The authors measured f-PSA and t-PSA in 36 men with untreated PCa (tumor classification: T1, 2, 3pNO, MO), 44 patients with BPH, and 54 healthy controls. Prostate volume was determined by transrectal ultrasound.
  
  
  RESULTS
  The median values of t-PSA and f-PSA% were 7.8 micrograms/L and 10.5% in PCa patients, 4.3 micrograms/L and 20.8% in patients with BPH, and 1.4 micrograms/L and 23.6% in the control group. Patients with PCa had a significantly lower proportion of f-PSA than BPH patients and healthy men. There was no correlation of f-PSA% to TNM stage or tumor grade. In PCa patients a significant positive correlation (correlation coefficient [r] = 0.51, P < 0.001) was found between f-PSA% and prostate volume, whereas there was no significant correlation in BPH patients (r = -0.27, P > 0.05). There was a significant difference in f-PSA% between PCa and BPH patients with prostate volumes smaller than 40 cm3 (9.0% vs. 21.6%, P < 0.01) but not between patients in these 2 groups with prostate volumes exceeding 40 cm3 (15.1% vs. 18.2%, P = 0.11).
  
  
  CONCLUSIONS
  Determining the ratio of f-PSA to t-PSA to discriminate between PCa and BPH patients yields significant results only in men with a prostate volume of less than 40 cm3.
authors.affiliation: Department of Urology, University Hospital Charité, Humboldt University Berlin, Germany.
authors.forename: C
authors.initials: C
authors.lastname: Stephan
authors.forename: M
authors.initials: M
authors.lastname: Lein
authors.forename: K
authors.initials: K
authors.lastname: Jung
authors.forename: D
authors.initials: D
authors.lastname: Schnorr
authors.forename: S A
authors.initials: SA
authors.lastname: Loening
mesh_terms: D000368:Aged; D003937:Diagnosis, Differential; D006801:Humans; D008297:Male; D008875:Middle Aged; D009367:Neoplasm Staging; D011467:Prostate / Q000473:pathology*; D017430:Prostate-Specific Antigen / Q000097:blood*; D011470:Prostatic Hyperplasia / Q000097:blood* / Q000473:pathology*; D011471:Prostatic Neoplasms / Q000097:blood* / Q000473:pathology*; D012680:Sensitivity and Specificity
chemical_list: D017430:Prostate-Specific Antigen