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Downgrading of biopsy based Gleason score in prostatectomy specimens
  1. Kilian M Treurniet1,
  2. Dominique Trudel2,3,
  3. Jenna Sykes4,
  4. Andrew J Evans3,
  5. Antonio Finelli5,
  6. Theodorus H Van der Kwast3
  1. 1Leiden University Medical Centre, Leiden, The Netherlands
  2. 2Cancer Research Center, Laval University, Quebec City, Quebec, Canada
  3. 3Department of Pathology, University Health Network, Toronto, Ontario, Canada
  4. 4Department of Biostatistics, University Health Network, Toronto, Ontario, Canada
  5. 5Division of Urology, Department of Surgical Oncology, University Health Network, University of Toronto, Canada
  1. Correspondence to Dr T van der Kwast, Department of Pathology, University Health Network, Toronto General Hospital, 200 Elizabeth Street, Toronto, Canada M5G 2C4; theo.vdkwast{at}uhn.ca

Abstract

Aims To assess the frequency and possible causes of downgrading from a Gleason score (GS) 7 at biopsy to a GS ≤6 at radical prostatectomy (RP) in a Canadian referral centre.

Methods Data were extracted from diagnostic reports of inhouse biopsies and matching prostatectomy specimens from 2008 to 2011 with a GS 7 at biopsy. Biopsies and corresponding prostatectomy specimens of downgraded cases were reviewed. Pathological features were assessed and possible predictors for downgrading were identified.

Results Based on pathology reports, 29 (8.9%, 95% CI 5.8% to 11.9%) of the 327 eligible cases were downgraded from biopsy GS 7 to RP GS 6, 72% of them representing a GS ≤6 with tertiary grade 4 at RP. Agreement at review of downgraded RP specimens for Gleason grading was fair and of borderline significance (κ=0.34, 95% CI −0.01 to 0.68, p=0.055) with 65% agreement for tertiary grade. The predominant Gleason grade 4 pattern found in the downgraded biopsies was ill-formed glands. The number of cores with Gleason grade 4 component was found to be the strongest negative predictor of downgrading (prereview OR=0.56 (95% CI 0.39 to 0.80, p=0.002), postreview OR=0.19 (95% CI 0.07 to 0.52, p=0.001)).

Conclusions The frequency of GS 7 in biopsies subsequently downgraded in RP is low and is associated with International Society of Urological Pathology modified Gleason grade 4 patterns. Downgrading could be attributed in most cases to the presence of a tertiary Gleason grade 4 pattern in the RP specimen. Inter-observer agreement for the presence of tertiary grade 4 in RP specimens is moderate.

  • Prostate
  • Cancer
  • Diagnostics
  • Genitourinary Pathology

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