title: Serum percent-free PSA does not predict extraprostatic spread of prostate cancer.
abstract: Percent-free prostate-specific antigen (proportion of free prostate-specific antigen [PSA] to total PSA) has been shown recently in studies on frozen serum samples to be more useful than total PSA alone in distinguishing prostate cancer from benign conditions of the prostate gland. The primary purpose of our study was to determine whether percent-free PSA could predict extraprostatic spread of prostate cancer. We also sought to evaluate the freeze-thaw stability of free PSA. Percent-free PSA values in fresh serum samples were compared with those in aliquots subjected to one to five freeze-thaw cycles. Percent-free PSA values in frozen serum samples from 130 men undergoing radical prostatectomy for clinically localized prostate cancer were compared across pathologic stages. Free PSA levels remained stable for up to five freeze-thaws. Great overlap was found in percent-free PSA values for men with organ-confined disease and those with extraprostatic spread. These results indicate that multiple freeze-thaw cycles do not significantly affect free PSA levels and percent-free PSA is not useful in identifying ideal candidates for radical prostatectomy.
authors.affiliation: Department of Pathology, The University of Michigan Medical Center, Ann Arbor 48109-0054, USA.
authors.forename: W H
authors.initials: WH
authors.lastname: Henricks
authors.forename: B G
authors.initials: BG
authors.lastname: England
authors.forename: D A
authors.initials: DA
authors.lastname: Giacherio
authors.forename: J E
authors.initials: JE
authors.lastname: Oesterling
authors.forename: K J
authors.initials: KJ
authors.lastname: Wojno
mesh_terms: D000230:Adenocarcinoma / Q000097:blood / Q000473:pathology* / Q000601:surgery; D000328:Adult; D000368:Aged; D004355:Drug Stability; D005615:Freezing; D006801:Humans; D008297:Male; D008875:Middle Aged; D009367:Neoplasm Staging; D017430:Prostate-Specific Antigen / Q000097:blood*; D011468:Prostatectomy; D011471:Prostatic Neoplasms / Q000097:blood / Q000473:pathology* / Q000601:surgery; D012372:ROC Curve
chemical_list: D017430:Prostate-Specific Antigen