Evaluation of concordance of Gleason score between prostate biopsy and radical prostatectomy.

Background: Histological Gleason score grading is a main determinant of prostate cancer treatment. However, the final histological examination may reveal that concordance rates between biopsy and pathological Gleason sums are inadequate.
Aim: To evaluate the concordance of Gleason score between prostate biopsy and radical prostatectomy specimen and to study factors predictive of up-grading of Gleason score at radical prostatectomy.
Methods: We conducted a descriptive and retrospective study including cases of patients who underwent  prostatectomy between 2008 and 2015. We proceeded to a histological examination of 30 cases of radical prostatectomy and 17 corresponding biopsies. The data of the remaining 13 prostate biopsies, not performed in our hospital, have been picked from detailed histological reports.
Results: Our results showed that the concordance in the Gleason score was 43% (kappa = 0.11, poor agreement).Gleason score was upgraded in 54% of the cases. At radical prostatectomy, it increased by two  points in one case and by one point in 14 cases. The Gleason score was under-graded on prostatic biopsies in an only 1 case. Using the new classification ISUP 2014, the concordance rate was 26% (kappa = 0.04,  very poor agreement). Gleason score was upgraded in 78% of the cases for Group 1 (SG 3 + 3) and 63% for group 2 (SG 3 + 4). The concordance rate was highest for Group 4 (4 + 3). Variables as age, serum PSA (prostate specific antigen) , numbre of cores, percentage of positive cores, or prostate volume were not significant predictors of upgrading of Gleason score on radical prostatectomy specimen.
Conclusion: Thus, the high rate of discordance of Gleason score between prostate biopsy and radical prostatectomy specimen implies an understanding of factors predictive of discordance of this score allowing urologists, pathologists and oncologists to support patients in a more suitable way, choosing the appropriate therapeutic modality for each patient.