title: Magnetic resonance imaging for predicting prostate biopsy findings in patients considered for active surveillance of clinically low risk prostate cancer.
abstract: OBJECTIVE
  A barrier to the acceptance of active surveillance for men with prostate cancer is the risk of underestimating the cancer burden on initial biopsy. We assessed the value of endorectal magnetic resonance imaging in predicting upgrading on confirmatory biopsy in men with low risk prostate cancer.
  
  
  METHODS
  A total of 388 consecutive men (mean age 60.6 years, range 33 to 89) with clinically low risk prostate cancer (initial biopsy Gleason score 6 or less, prostate specific antigen less than 10 ng/ml, clinical stage T2a or less) underwent endorectal magnetic resonance imaging before confirmatory biopsy. Three radiologists independently and retrospectively scored tumor visibility on endorectal magnetic resonance imaging using a 5-point scale (1-definitely no tumor to 5-definitely tumor). Inter-reader agreement was assessed with weighted kappa statistics. Associations between magnetic resonance imaging scores and confirmatory biopsy findings were evaluated using measures of diagnostic performance and multivariate logistic regression.
  
  
  RESULTS
  On confirmatory biopsy, Gleason score was upgraded in 79 of 388 (20%) patients. Magnetic resonance imaging scores of 2 or less had a high negative predictive value (0.96-1.0) and specificity (0.95-1.0) for upgrading on confirmatory biopsy. A magnetic resonance imaging score of 5 was highly sensitive for upgrading on confirmatory biopsy (0.87-0.98). At multivariate analysis patients with higher magnetic resonance imaging scores were more likely to have disease upgraded on confirmatory biopsy (odds ratio 2.16-3.97). Inter-reader agreement and diagnostic performance were higher for the more experienced readers (kappa 0.41-0.61, AUC 0.76-0.79) than for the least experienced reader (kappa 0.15-0.39, AUC 0.61-0.69). Magnetic resonance imaging performed similarly in predicting low risk and very low risk (Gleason score 6, less than 3 positive cores, less than 50% involvement in all cores) prostate cancer.
  
  
  CONCLUSIONS
  Adding endorectal magnetic resonance imaging to the initial clinical evaluation of men with clinically low risk prostate cancer helps predict findings on confirmatory biopsy and assess eligibility for active surveillance.
authors.affiliation: Department of Radiology, Memorial Sloan-Kettering Cancer Center, New York, New York, USA. vargasah@mskcc.org
authors.forename: Hebert Alberto
authors.initials: HA
authors.lastname: Vargas
authors.forename: Oguz
authors.initials: O
authors.lastname: Akin
authors.forename: Asim
authors.initials: A
authors.lastname: Afaq
authors.forename: Debra
authors.initials: D
authors.lastname: Goldman
authors.forename: Junting
authors.initials: J
authors.lastname: Zheng
authors.forename: Chaya S
authors.initials: CS
authors.lastname: Moskowitz
authors.forename: Amita
authors.initials: A
authors.lastname: Shukla-Dave
authors.forename: James
authors.initials: J
authors.lastname: Eastham
authors.forename: Peter
authors.initials: P
authors.lastname: Scardino
authors.forename: Hedvig
authors.initials: H
authors.lastname: Hricak
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D001706:Biopsy; D006801:Humans; D008279:Magnetic Resonance Imaging; D008297:Male; D008875:Middle Aged; D011237:Predictive Value of Tests; D011471:Prostatic Neoplasms / Q000473:pathology*; D012189:Retrospective Studies; D018570:Risk Assessment; D057832:Watchful Waiting