A new prostate cancer biopsy reporting system with prognostic potential.

Abstract

e16572 Background: Presently, prostate biopsy (PBx) results typically report the highest Gleason Grade Group in the PBx as the single metric used to gauge the clinical aggressiveness of tumor and dictate treatment. However, using that single parameter alone limits the clinician by lack of consideration of the entire PBx. Intuitively we presumed that a PBx showing multiple cores of cancer would represent more aggressive disease. Herein, we propose the Weighted Gleason Grade Group (WGGG), a novel scoring system that synthesizes histopathologic data and cancer volume into a single numeric value representing the entire PBx, allowing the urologist to more accurately predict adverse pathologic outcomes of radical prostatectomy (RP). Methods: We studied 246 men who underwent RP after standard multi-core PBx. The highest Gleason score of each PBx was converted to its final GGG. The WGGG was calculated by summing the Gleason score of each positive core and normalized for a 12 core total. RP pathology was studied to determine adverse pathological outcomes, specifically, extraprostatic extension (EPE), positive surgical margins (PSM), seminal vesical invasion (SVI), pathological up-grading and any adverse feature. We then studied the ability of conventional GGG versus WGGG to have ‘predicted’ the risk of these adverse features comparing their respective receiver operating characteristic (ROC) areas under the curve (AUC) for each, as well as any adverse feature. Results: The AUC for the WGGG vs. GGG was significantly higher for predicting EPE (AUC 0.782 vs. 0.697, respectively; z = -3.29; p = .0009), PSM (AUC 0.644 vs. 0.563, respectively; z = -3.00; p = .0027), SVI (AUC 0.829 vs. 0.713, respectively; z = -3.05; p = .0023) and pathologic up-grading (AUC 0.584 vs. 0.349, respectively; z = -3.13; p = .002). Finally, the AUC for any adverse feature was 0.637 for WGGG versus 0.556 for GGG; z = -3.29; p = .001. Conclusions: The WGGG, by providing a metric reflecting the entirety of the PBx, is more informative than conventional single GGG alone in ‘predicting’ adverse pathologic outcomes on radical prostatectomy specimens. We are now studying if % cancer/ PBx core will improve WGGG performance.