Concordance between Gleason scores of needle biopsies and radical prostatectomy specimens: a population‐based study

Abstract

To study the concordance between the Gleason scores of needle biopsies and radical prostatectomy (RP) specimens in a population-based registry, to clarify whether the concordance depends on the annual number of RP specimens assessed in the pathology unit, and to identify preoperative clinical factors that predict upgrading from a Gleason score of <or=6 in the biopsy to >or=7 in the RP specimen. Through the Cancer Registry of Norway, we identified 1116 patients with available Gleason scores from biopsy and RP specimens. Concordance was evaluated using the kappa coefficient, and predictors of concordance were assessed in univariate and multivariate logistic regression analyses. The Gleason scores were identical in biopsy and RP specimens in 591 of the 1116 (53%) patients. The biopsy-based Gleason score more often under-graded (38%) than over-graded (9%) the RP-based Gleason score. Pathology units that examined >40 RP specimens annually had a higher concordance between the Gleason score in the biopsy and RP specimen than did lower-volume units. The rate of upgrading from a Gleason score of <or=6 in the biopsy to >or=7 in the RP specimen increased with increasing preoperative prostate-specific antigen serum levels, and with increasing intervals between biopsy and RP. The concordance in Gleason score between biopsy and RP was highest among the pathology departments that regularly evaluated RP specimens. Careful consideration of clinical factors and biopsy grading might improve the identification of patients considered as suitable for active surveillance.