title: Importance and determinants of Gleason score undergrading on biopsy sample of prostate cancer in a population-based study.
abstract: BACKGROUND
  In this population-based study, we investigated the degree of concordance between Gleason scores obtained from prostate biopsies and those obtained from prostatectomy specimens, as well as the determinants of biopsy understaging.
  
  
  METHODS
  We considered for this study all 371 prostate cancer patients recorded at the Geneva Cancer Registry diagnosed from 2004 to 2006 who underwent a radical prostatectomy. We used the kappa statistic to evaluate the Gleason score concordance from biopsy and prostatectomy specimens. Logistic regression was used to determine the parameters that predict the undergrading of the Gleason score in prostate biopsies.
  
  
  RESULTS
  The kappa statistic between biopsy and prostatectomy Gleason score was 0.42 (p < 0.0001), with 67% of patients exactly matched, and 26% (n = 95) patients with Gleason score underestimated by the biopsy. In a multi-adjusted model, increasing age, advanced clinical stage, having less than ten biopsy cores, and longer delay between the two procedures, were all independently associated with biopsy undergrading. In particular, the proportion of exact match increased to 72% when the patients had ten or more needle biopsy cores. The main limitation of the study is that both biopsy and prostatectomy specimens were examined by different laboratories.
  
  
  CONCLUSIONS
  The data show that concordance between biopsy and prostatectomy Gleason scores lies within the classic clinical standards in this population-based study. The number of biopsy cores appears to strongly impact on the concordance between biopsy and radical prostatectomy Gleason score.
authors.affiliation: Geneva Cancer Registry, Institute for Social and Preventive Medicine, University of Geneva, 55 Boulevard de la Cluse, 1205 Geneva, Switzerland. elisabetta.rapiti@unige.ch
authors.forename: Elisabetta
authors.initials: E
authors.lastname: Rapiti
authors.forename: Robin
authors.initials: R
authors.lastname: Schaffar
authors.forename: Christophe
authors.initials: C
authors.lastname: Iselin
authors.forename: Raymond
authors.initials: R
authors.lastname: Miralbell
authors.forename: Marie-Françoise
authors.initials: MF
authors.lastname: Pelte
authors.forename: Damien
authors.initials: D
authors.lastname: Weber
authors.forename: Roberto
authors.initials: R
authors.lastname: Zanetti
authors.forename: Isabelle
authors.initials: I
authors.lastname: Neyroud-Caspar
authors.forename: Christine
authors.initials: C
authors.lastname: Bouchardy
mesh_terms: D000230:Adenocarcinoma / Q000473:pathology*; D000367:Age Factors; D000368:Aged; D062005:Biopsy, Large-Core Needle; D015331:Cohort Studies; D003951:Diagnostic Errors; D006801:Humans; D016015:Logistic Models; D008297:Male; D008875:Middle Aged; D060787:Neoplasm Grading / Q000706:statistics & numerical data*; D009367:Neoplasm Staging; D011467:Prostate / Q000473:pathology; D011468:Prostatectomy; D011471:Prostatic Neoplasms / Q000473:pathology*; D013557:Switzerland