MP09-17\u2003WEIGHTED GLEASON GRADE GROUP (WGGG): A NEW PROSTATE CANCER BIOPSY REPORTING SYSTEM WITH PROGNOSTIC POTENTIAL

Abstract

INTRODUCTION AND OBJECTIVES: Presently, prostate biopsy (PBx) results report the highest Gleason Grade Group (GGG) as a metric to gauge the overall aggressiveness of cancer and dictate treatment. Intuitively, we presumed a PBx showing multiple cores of cancer with more volume cancer per core would represent more aggressive disease. We previously proposed the Weighted Gleason Grade Group (WGGG), a novel scoring system that synthesizes all histopathologic data and cancer volume into a single numeric value representing the entire PBx, to more accurately predict adverse pathologic outcomes of radical prostatectomy (RP). This work is now extended to a second database at another institution to assess this latter potential. METHODS: We studied 171 men who underwent RP after standard multi-core PBx at a single academic institution. WGGG was calculated by summing the values of each positive core described by the formula: GGG + (GGG x % Ca/core), and normalized for a 12-core total, for a possible value ranging from 1 to 120. RP pathology was assessed for extraprostatic extension (EPE), seminal vesical invasion (SVI), lymph node involvement (LNI), and positive surgical margins (PSM). We compared GGG vs WGGG receiver operating characteristic (ROC) areas under the curve (AUC) for each adverse feature. We then used a second group of 389 men from another academic institution to confirm the discriminatory advantage of WGGG. RESULTS: Baseline characteristics for both cohorts are listed in the Table. For the development group, the AUCs for the WGGG vs. GGG were significantly higher for predicting EPE (0.78 vs. 0.69, p=0.002), SVI (AUC 0.82 vs. 0.72, p=0.014), LNI (AUC 0.86 vs. 0.82, p=0.039) and PSM (AUC 0.64 vs. 0.58, p=0.031). Discriminatory advantage was confirmed in the validation cohort: EPE (AUC 0.76 vs. 0.73 p=0.13), SVI (AUC 0.82 vs. 0.75 p=0.01), LNI (AUC 0.94 vs. 0.87 p 0.02), PSM (AUC 0.62 vs. 0.55 p=0.04). 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 RP specimens. This superior discriminatory capability has been achieved without any consideration of other available clinical disease characteristics and should help the urologist to better evaluate his patient candidates for RP. Table. No title available. Source of Funding: None