Login to Access Video or Poster Abstract: MP20-13
Sources of Funding: none

Introduction

Commonly used Gleason score grading of prostate cancer presents various deficiencies. Recently a new 5 Grade Group system has been developed sub-stratifying standard Biopsy Gleason scores 6, 3+4, 4+3, 8 and 9-10 into 5 distinct, prognostic Groups 1-5. We sought to replicate this new grading system for surgical Gleason score on a large contemporary Canadian cohort._x000D_ _x000D_

Methods

Analysis was realized on pathologic specimens of a prospectively maintained Canadian database of men who underwent robot-assisted radical prostatectomy (RARP) between 2006 and 2016 at two major academic centers in Montreal. Outcome was based on biochemical recurrence (BCR) defined as a rising PSA>0.2ng/mL. The log-rank test assessed univariable differences in BCR by the novel Gleason score groups from prostate biopsy. Separate univariable and multivariable Cox proportional hazards used four possible categorizations of Gleason scores.

Results

Of the 617 patients eligible for analysis, 102, 398, 57, 34, 26 were classified as group 1,2,3,4,5 respectively. With a mean follow-up of 28 months, significant differences in BCR rates between both Gleason 3 + 4 versus 4 + 3 (p<0.001) were observed. There were no statistical difference in BCR rates between Gleason 8 versus 9-10 (p= 0.342). The hazard ratios relative to Gleason score 6 were 1.531 95% CI (0.588; 3.987), 5.146 (1.754; 15.098), 8.157 (2.783; 23.911), and 11.7 (3.585; 30.804) for Gleason scores 3 + 4, 4 + 3, 8, and 9–10, respectively. _x000D_

Conclusions

The present study demonstrates the importance of the separation of the two Gleason categories 3+4 versus 4+3 in the new system. Further studies are warranted to implement the updated system for more accurate prognostications, and to improve patient counseling of cancer grading.

Funding

none