Evaluation of Gleason Grade Group 5 in a Contemporary Prostate Cancer Grading System and Literature Review.

Abstract

The aim of this study was to validate contemporary grading systems, in particular, the Gleason grade group (GGG)5. We retrospectively reviewed the clinicopathologic data of 176 patients who underwent radical prostatectomy and whose pathologic results were GGG 4 or 5. The endpoints were biochemical recurrence (BCR) and castration-resistant prostate cancer (CRPC). The GGG 4 group was composed of 69 patients. The GGG 5 group consisted of 78 patients with GS 4+5 and 29 patients with GS 5+4 or higher. The 5-year BCR-free survival rates for men with GGG 4, GS 4+5, and GS 5+4 or higher were 59%, 54%, and 20%, respectively, and the 5-year CRPC-free survival rates were 98%, 100%, and 88%, respectively. Both the BCR- and CRPC-free survival rates were significantly higher in GS 4+5 than in GS 5+4 or higher (P< .001 and P= .002, respectively), but there were no significant differences between GGG 4 and GS 4+5 (P= .702 and P= .803, respectively). The multivariate analysis demonstrated that GS 5+4 or higher (hazard ratio, 3.4; P= .002) and lymphovascular invasion (hazard ratio, 3.4; P< .001) greatly affected BCR. Our follow-up study revealed that men with GS 4+5 and those with GGG 4 had a similar prognosis. However, there was a significant discrepancy in prognosis between GS 4+5 and GS 5+4 or higher. This suggested that GGG 4 and 5 in the contemporary prostate cancer grading system should be reviewed. Furthermore, lymphovascular invasion may be useful to subgroup these pathologically high-risk patients.