title: Biologic variability of prostate-specific antigen and its usefulness as a marker for prostate cancer: effects of finasteride. Finasteride PSA Study Group.
abstract: OBJECTIVE
  The effects of finasteride on prostate-specific antigen (PSA) variability and usefulness in prostate cancer detection were examined.
  
  
  METHODS
  Percent change and crossover of PSA levels between the low (1.0 to 3.9 ng/mL) and high (4.0 to 10.0 ng/mL) ranges were evaluated in 72 men with benign prostatic hyperplasia (BPH) and 77 men with both BPH and prostate cancer (PCa) treated with finasteride or placebo for 6 months. Patients with PCa were studied as a model for evaluating the effects on PSA levels in patients with BPH and latent PCa. As recommended on the product label, PSA levels for finasteride-treated patients were doubled for interpretation.
  
  
  RESULTS
  In patients with BPH, most placebo- and finasteride-treated patients with low PSA levels at baseline had subsequent PSA levels below 4.0 ng/mL throughout the study. Among patients with high baseline PSA levels, only 1 of 17 finasteride-treated patients, compared with 8 of 13 placebo-treated patients, crossed into the low range. In the BPH/PCa study, most placebo-treated patients maintained PSA levels in the same range (15 of 19 less than 4.0 ng/mL; 14 of 16 greater than 4.0 ng/mL). Almost one third of finasteride-treated patients with low PSA levels at baseline crossed into the high range (8 of 22), whereas most patients with high PSA levels at baseline were not masked with treatment, with PSA levels remaining high (12 of 15).
  
  
  CONCLUSIONS
  PSA levels cross between the low and high PSA ranges in both finasteride- and placebo-treated patients with BPH and those with both BPH and PCa. Doubling the PSA levels in finasteride-treated patients allows appropriate interpretation of PSA values and does not mask the detection of PCa.
authors.affiliation: Mayo Clinic, Rochester, Minnesota, USA.
authors.forename: J E
authors.initials: JE
authors.lastname: Oesterling
authors.forename: J
authors.initials: J
authors.lastname: Roy
authors.forename: A
authors.initials: A
authors.lastname: Agha
authors.forename: T
authors.initials: T
authors.lastname: Shown
authors.forename: T
authors.initials: T
authors.lastname: Krarup
authors.forename: T
authors.initials: T
authors.lastname: Johansen
authors.forename: M
authors.initials: M
authors.lastname: Lagerkvist
authors.forename: G
authors.initials: G
authors.lastname: Gormley
authors.forename: M
authors.initials: M
authors.lastname: Bach
authors.forename: J
authors.initials: J
authors.lastname: Waldstreicher
mesh_terms: D000328:Adult; D000368:Aged; D014408:Biomarkers, Tumor / Q000097:blood*; D004791:Enzyme Inhibitors / Q000627:therapeutic use*; D018120:Finasteride / Q000627:therapeutic use*; D006801:Humans; D008297:Male; D008875:Middle Aged; D017430:Prostate-Specific Antigen / Q000097:blood* / Q000187:drug effects; D011471:Prostatic Neoplasms / Q000097:blood* / Q000188:drug therapy*
chemical_list: D014408:Biomarkers, Tumor; D004791:Enzyme Inhibitors; D018120:Finasteride; D017430:Prostate-Specific Antigen