title: Validity of prostate-specific antigen as a tumour marker in men with prostate cancer managed by watchful-waiting: correlation with findings at serial endorectal magnetic resonance imaging and spectroscopic imaging.
abstract: OBJECTIVE
  To investigate the validity of prostate-specific antigen (PSA) as a tumour marker in men with clinically localized prostate cancer who have selected watchful waiting, by determining if serial PSA level measurements are correlated with findings of malignancy or benign prostatic hyperplasia (BPH) at serial endorectal magnetic resonance imaging (MRI) and magnetic resonance spectroscopic imaging (MRSI).
  
  
  METHODS
  We retrospectively identified 69 men with biopsy-proven prostate cancer being managed by watchful waiting, who underwent serial endorectal MRI/MRSI and who had contemporaneous serial PSA measurements. The mean (range) follow-up was 392 (294-571) days. A panel of three experienced readers reviewed the initial and follow-up MRI/MRSI studies, and classified findings of prostate cancer as stable or progressive. Another reader assessed BPH by calculating total gland and central gland volumes on all studies.
  
  
  RESULTS
  At the follow-up MRI/MRSI, 51, 17 and one patient had stable, progressive, or unevaluable prostate cancer, respectively. The mean PSA velocity was significantly greater in patients with radiologically progressive disease (1.42 vs 0.42 ng/mL/year, P = 0.04). A PSA velocity of >0.75 ng/mL/year identified those with radiologically progressive disease with a true-positive fraction of 0.71 and a false-positive fraction of 0.39. PSA levels were not correlated with changes in total or central gland volumes (P > 0.05).
  
  
  CONCLUSIONS
  In men with clinically localized prostate cancer who select watchful waiting, serial PSA levels are correlated with findings of malignancy but not BPH at serial endorectal MRI/MRSI, suggesting that PSA is a useful longitudinal tumour marker in this population.
authors.affiliation: Department of Urology, The University of California at San Francisco, San Francisco, CA, USA. fergus.coakley@radiology.ucsf.edu
authors.forename: Fergus V
authors.initials: FV
authors.lastname: Coakley
authors.forename: Irene
authors.initials: I
authors.lastname: Chen
authors.forename: Aliya
authors.initials: A
authors.lastname: Qayyum
authors.forename: Antonio C
authors.initials: AC
authors.lastname: Westphalen
authors.forename: Peter R
authors.initials: PR
authors.lastname: Carroll
authors.forename: Hedvig
authors.initials: H
authors.lastname: Hricak
authors.forename: Mei-Hsiu
authors.initials: MH
authors.lastname: Chen
authors.forename: John
authors.initials: J
authors.lastname: Kurhanewicz
mesh_terms: D000368:Aged; D000369:Aged, 80 and over; D005500:Follow-Up Studies; D006801:Humans; D008279:Magnetic Resonance Imaging; D009682:Magnetic Resonance Spectroscopy; D008297:Male; D008875:Middle Aged; D017430:Prostate-Specific Antigen / Q000097:blood*; D011470:Prostatic Hyperplasia / Q000097:blood / Q000473:pathology*; D011471:Prostatic Neoplasms / Q000097:blood / Q000473:pathology*; D015203:Reproducibility of Results; D012189:Retrospective Studies
chemical_list: D017430:Prostate-Specific Antigen