External validation of the novel International Society of Urological Pathology (ISUP) Gleason grading groups in a large contemporary Canadian cohort

Prognostic Utility of the Gleason Grading System Revisions and Histopathological Factors Beyond Gleason Grade

Background

The International Society of Urological Pathology (ISUP) revised the Gleason system in 2005 and 2014. The impact of these changes on prostate cancer (PCa) prognostication remains unclear.

Objective

To evaluate if the ISUP 2014 Gleason score (GS) predicts PCa death better than the pre-2005 GS, and if additional histopathological information can further improve PCa death prediction.

Patients and Methods

We conducted a case–control study nested among men in the National Prostate Cancer Register of Sweden diagnosed with non-metastatic PCa 1998–2015. We included 369 men who died from PCa (cases) and 369 men who did not (controls). Two uro-pathologists centrally re-reviewed biopsy ISUP 2014 Gleason grading, poorly formed glands, cribriform pattern, comedonecrosis, perineural invasion, intraductal, ductal and mucinous carcinoma, percentage Gleason 4, inflammation, high-grade prostatic intraepithelial neoplasia (HGPIN) and post-atrophic hyperplasia. Pre-2005 GS was back-transformed using i) information on cribriform pattern and/or poorly formed glands and ii) the diagnostic GS from the registry. Models were developed using Firth logistic regression and compared in terms of discrimination (AUC).

Results

The ISUP 2014 GS (AUC = 0.808) performed better than the pre-2005 GS when back-transformed using only cribriform pattern (AUC = 0.785) or both cribriform and poorly formed glands (AUC = 0.792), but not when back-transformed using only poorly formed glands (AUC = 0.800). Similarly, the ISUP 2014 GS performed better than the diagnostic GS (AUC = 0.808 vs 0.781). Comedonecrosis (AUC = 0.811), HGPIN (AUC = 0.810) and number of cores with ≥50% cancer (AUC = 0.810) predicted PCa death independently of the ISUP 2014 GS.

Conclusion

The Gleason Grading revisions have improved PCa death prediction, likely due to classifying cribriform patterns, rather than poorly formed glands, as Gleason 4. Comedonecrosis, HGPIN and number of cores with ≥50% cancer further improve PCa death discrimination slightly.

External validation of the Gleason grade group system in Argentinian patients that underwent surgery for prostate cancer

Introduction

The aim of this article was to evaluate the effectiveness of the Gleason grade groups (GGG) system on a group of Argentinian patients with prostate cancer (PC) who underwent radical prostatectomy (RP).

Material and methods

We retrospectively studied 262 patients who underwent RP between 1996 and 2014. To determine the performance and validity of the GGG system, a Kaplan-Meier analysis and multivariate analysis with Cox proportional method were performed to evaluate biochemical recurrence, distance metastases and specific cancer mortality. The area under the curve (AUC) was calculated to compare new groups of degrees of the GGG system with the classical scheme of stratification into 3 groups.

Results

The median follow-up was 84 months. As the groups ascend, there is less confined organ disease (p <0.001) and greater extraprostatic extension (p <0.001), greater invasion of seminal vesicles (p <0.001) and greater lymph node involvement (p <0.001). The biochemical recurrence-free survival at 5 years was 68%, 55%, 22%, 9%, 0% of the 1–5 groups, respectively. Ten-years cancer-specific survival was 96%, 95%, 78%, 64%, 25% for group 1–5, respectively. In the multivariate analysis, the GGG system is presented as the only independent predictor of biochemical recurrence and specific cancer mortality. The AUC indicates that the GGG system has a higher prognostic discrimination compared to the classic 3-group system (6, 7, ≥8).

Conclusions

The International Society of Urological Pathology (ISUP) GGG system is an independent predictor of biochemical recurrence and mortality from prostate cancer in patients treated with RP. The classification into 5 groups shows greater discrimination in the prognosis than the traditional Gleason classification.