Interobserver agreement of gleason score and modified gleason score in needle biopsy and in surgical specimen of prostate cancer

Abstract

Introduction:Gleason score, which has a high interobserver variability, is used to classify prostate cancer. The most recent consensus valued the tertiary Gleason pattern and recommended its use in the final score of needle biopsies (modified Gleason score). This pattern is considered to be of high prognostic value in surgical specimens. This study emphasized the evaluation of the modified score agreement in needle biopsies and in surgical specimen, as well as the interobserver variability of this score. Materials and Methods: Three pathologists evaluated the slides of needle biopsies and surgical specimens of 110 patients, reporting primary, secondary and tertiary Gleason patterns and after that, traditional and modified Gleason scores were calculated. Kappa test (K) assessed the interobserver agreement and the agreement between the traditional and modified scores of the biopsy and of the surgical specimen. Results: Interobserver agreement in the biopsy was K = 0.36 and K = 0.35, and in the surgical specimen it was K = 0.46 and K = 0.36, for the traditional and modified scores, respectively. The tertiary Gleason grade was found in 8%, 0% and 2% of the biopsies and in 8%, 0% and 13% of the surgical specimens, according to observers 1, 2 and 3, respectively. When evaluating the agreement of the traditional and modified Gleason scores in needle biopsy with both scores of the surgical specimen, a similar agreement was found through Kappa. Conclusion:Contrary to what was expected, the modified Gleason score was not superior in the agreement between the biopsy score and the specimen, or in interobserver reproducibility, in this study.

Blinded review of archival radical prostatectomy specimens supports that contemporary Gleason score 6 prostate cancer lacks metastatic potential

“…Because the pathologist was aware of both the metastatic outcome and the study hypothesis that Gleason pattern >4 is present in metastatic pGS6 RP specimens, the potential for upgrading bias must be considered, particularly in cases with a very small volume of Gleason pattern 4. A second independent pathologist review was not involved despite the practical subjectivity and inter‐observer variability of Gleason scoring . Similarly, Kweldam et al reviewed six RP specimens associated with distant or pelvic metastases among 449 pGS6 patients.…”

“…However, a limitation of these studies is that regrading was performed by a single pathologist who was aware of the metastasis outcomes and study objectives, which introduces potential for upgrading bias. Given the practical subjectivity and inter‐observer variability of Gleason score assignment, these findings require confirmation using an unbiased study design with multiple independent blinded pathologists.…”

Current Perspectives on Gleason Grading of Prostate Cancer

“…One study found a higher percentage agreement by chisquare test (P<0.001), although κ statistics were not done [48]. Another study, using κ statistics and three pathologist evaluators, found no improvement in concordance or in interobserver reproducibility [49].…”

Implications of the International Society of Urological Pathology Modified Gleason Grading System

“…18,23,24 In a study by Uemura et al, 23 the concordance rates for needle biopsies and radical prostatectomy specimens between the original Gleason system and the ISUP modified system were 67% and 70%, respectively. Similarly, Zareba et al 18 showed the biopsyradical prostatectomy did not significantly affect the Gleason score agreement (63.4% and 65.5%, respectively).…”