Prognostic value of percent Gleason grade 4 at prostate biopsy on predicting prostatectomy pathology and recurrence.

PURPOSE - The importance of primary Gleason grade among men with Gleason score 7 disease has been well defined. However, this dichotomization may overly simplify the continuous spectrum of absolute percent Gleason grade 4 disease (G4%).

Herein, we report the prognostic value of G4% on cancer-related outcomes of men undergoing radical prostatectomy (RP).

METHODS - Patients undergoing RP for clinically localized Gleason 6-8 prostate cancer from 2005-2013 were included. G4% was determined as biopsy tumor length containing Gleason Pattern 4 / total tumor length, which performed better than alternative quantifications of pattern 4 involvement. G4% was correlated with time to biochemical recurrence (BCR) and presence of adverse RP pathology, defined as primary Gleason 4 or >pT3, by multivariable logistic and Cox regressions.

RESULTS - 517/1,691 patients (30.6%) had adverse pathological features, and 86 (5.6%) experienced BCR. On multivariable analyses, G4% was a significant predictor of adverse pathology (OR 1.04, 95% CI [1.03-1.05]) and time to BCR (HR 1.02 [1.01-1.03]). G4% was also a significant independent predictor of adverse pathology in subsets of patients with Gleason score 7 (OR 1.05 [1.03-1.06]), 3+4 (OR 1.06 [1.04-1.08]), and 4+3 cancer (OR 1.05 [1.03-1.06]). We demonstrate significantly increased risk of adverse pathology at potentially meaningful G4% thresholds (1-10% vs 20-30%).

CONCLUSIONS - The incremental percentage of Gleason grade 4 disease in biopsy specimens is an important predictor of adverse pathology and BCR across the entire range of G4% disease. Accounting for G4% can improve risk assessment even among those patients with Gleason 3+4 or 4+3 cancer and may help inform patient counseling.

The Journal of urology. 2016 Feb 23 [Epub ahead of print]

Adam I Cole, Todd M Morgan, Daniel E Spratt, Ganesh S Palapattu, Chang He, Scott A Tomlins, Alon Z Weizer, Felix Y Feng, Angela Wu, Javed Siddiqui, Arul M Chinnaiyan, Jeffrey S Montgomery, Lakshmi P Kunju, David C Miller, Brent K Hollenbeck, John T Wei, Rohit Mehra

Department of Urology, University of Michigan Medical School, Ann Arbor, MI, USA., Department of Urology, University of Michigan Medical School, Ann Arbor, MI, USA., Department of Radiation Oncology, University of Michigan Medical School, Ann Arbor, MI, USA., Department of Urology, University of Michigan Medical School, Ann Arbor, MI, USA; Comprehensive Cancer Center, University of Michigan Medical School, Ann Arbor, MI, USA., Department of Urology, University of Michigan Medical School, Ann Arbor, MI, USA., Department of Pathology, University of Michigan Medical School, Ann Arbor, MI, USA; Michigan Center for Translational Pathology, University of Michigan Medical School, Ann Arbor, MI, USA; Comprehensive Cancer Center, University of Michigan Medical School, Ann Arbor, MI, USA., Department of Urology, University of Michigan Medical School, Ann Arbor, MI, USA; Comprehensive Cancer Center, University of Michigan Medical School, Ann Arbor, MI, USA., Department of Radiation Oncology, University of Michigan Medical School, Ann Arbor, MI, USA., Department of Pathology, University of Michigan Medical School, Ann Arbor, MI, USA., Department of Pathology, University of Michigan Medical School, Ann Arbor, MI, USA., Department of Pathology, University of Michigan Medical School, Ann Arbor, MI, USA; Michigan Center for Translational Pathology, University of Michigan Medical School, Ann Arbor, MI, USA; Comprehensive Cancer Center, University of Michigan Medical School, Ann Arbor, MI, USA., Department of Urology, University of Michigan Medical School, Ann Arbor, MI, USA., Department of Pathology, University of Michigan Medical School, Ann Arbor, MI, USA; Michigan Center for Translational Pathology, University of Michigan Medical School, Ann Arbor, MI, USA., Department of Urology, University of Michigan Medical School, Ann Arbor, MI, USA., Department of Urology, University of Michigan Medical School, Ann Arbor, MI, USA., Department of Urology, University of Michigan Medical School, Ann Arbor, MI, USA., Department of Pathology, University of Michigan Medical School, Ann Arbor, MI, USA; Michigan Center for Translational Pathology, University of Michigan Medical School, Ann Arbor, MI, USA; Comprehensive Cancer Center, University of Michigan Medical School, Ann Arbor, MI, USA.