title: Values for free/total prostate-specific antigen ratio as a function of age: necessity of reference validation in a Turkish population.
abstract: BACKGROUND
  The aim of this study was to evaluate age-related changes in free/total prostate-specific antigen (f/t PSA) ratio, focusing on the avoidance of unnecessary prostate biopsies.
  
  
  METHODS
  A total of 898 men aged 30-88 years without a history of prostate surgery and disease were enrolled into the study. Serum tPSA, fPSA and f/t PSA ratios were determined for the study population and for different age categories. All males who had suspicious digital rectal examination and tPSA >4 ng/mL underwent transrectal ultrasonography-guided prostate biopsy. Receiver operating characteristic (ROC) curves for each group were generated by plotting the sensitivity vs. 1-specificity for the f/t PSA ratio. The sensitivity and specificity were obtained using different f/t PSA ratio cutoffs for different age groups.
  
  
  RESULTS
  Prostate cancer was detected in 63 patients (7%). Age-specific cutoffs were determined according to likelihood ratios at the levels of 10%, 15% and 15% f/t PSA ratio for ages 50-59, 60-69 and >/=70 years, respectively. However, a single cutoff of 10% is recommended across all age ranges (positive likelihood ratio 2.36). ROC curves demonstrated that the area under the curve (AUC) was significant for all patients with initial PSA of 4-10 ng/mL (AUC 0.703-0.796), except for the >/=70-year age group (AUC 0.549).
  
  
  CONCLUSIONS
  The current study showed that the use of f/t PSA ratio in patients with PSA levels of 4-10 ng/mL should enhance the specificity of PSA screening and decrease the number of unnecessary biopsies. f/t PSA levels may show dissimilarities according to age and ethnicity, so further studies are warranted to identify this relationship.
authors.affiliation: Department of Biochemistry, Zonguldak Karaelmas University, School of Medicine, Kozlu Zonguldak, Turkey. agmungan@yahoo.com
authors.forename: A Gorkem
authors.initials: AG
authors.lastname: Mungan
authors.forename: Bulent
authors.initials: B
authors.lastname: Erol
authors.forename: Bulent
authors.initials: B
authors.lastname: Akduman
authors.forename: Gurdal
authors.initials: G
authors.lastname: Bozdogan
authors.forename: Sibel
authors.initials: S
authors.lastname: Kiran
authors.forename: Cetin
authors.initials: C
authors.lastname: Yesilli
authors.forename: N Aydin
authors.initials: NA
authors.lastname: Mungan
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D000375:Aging / Q000097:blood*; D006801:Humans; D008297:Male; D008875:Middle Aged; D017430:Prostate-Specific Antigen / Q000097:blood*; D011470:Prostatic Hyperplasia / Q000175:diagnosis / Q000503:physiopathology; D011471:Prostatic Neoplasms / Q000175:diagnosis; D012372:ROC Curve; D012016:Reference Values; D012680:Sensitivity and Specificity; D014421:Turkey
chemical_list: D017430:Prostate-Specific Antigen