New Prostate Cancer Grading System Predicts Long-term Survival Following Surgery for Gleason Score 8-10 Prostate Cancer.

BACKGROUND: The newly proposed five-tiered prostate cancer grading system (PCGS) divides Gleason score (GS) 8-10 disease into GS 8 and GS 9-10 on the basis of biochemical recurrence (BCR) following radical prostatectomy (RP) as an outcome. However, BCR does not necessarily portend worse survival outcomes.

OBJECTIVE: To assess the significance of distinguishing GS 8 versus 9-10 disease in terms of long-term survival outcomes for both the preoperative setting using biopsy (Bx) GS and the postoperative setting with RP GS.

DESIGN, SETTING, AND PARTICIPANTS: Of 23918 men who underwent RP between 1984 and 2014, there were 721 men with biopsy GS 8-10, and 1047 men with RP GS 8-10.

OUTCOME MEASURES AND STATISTICAL ANALYSIS: Clinicopathologic characteristics were compared between men with GS 8 and those with GS 9-10. We compared all-cause mortality (ACM) and prostate cancer-specific mortality (PCSM) risk between the groups using Cox regression and competing-risks analyses, adjusting for other perioperative variables and death from other causes as the competing event.

RESULTS AND LIMITATIONS: Compared to men with GS 8, men with GS 9-10 had later RP year and higher pathologic stage. Among men with Bx GS 8-10, 115 died (82 due to PC) with median follow-up of 3 yr (interquartile range [IQR] 1-7) for both overall and cancer-specific survival. Of men with RP GS 8-10, 221 died (151 due to PC) with median follow-up of 4 yr (IQR 2-8) and 4 yr (IQR 2-9) for overall and cancer-specific survival, respectively. PC-specific survival rates were significantly lower for men with GS 9-10 compared to men with GS 8 for both Bx (hazard ratio [HR] 2.13, 95% confidence interval [CI] 1.37-3.30; p<0.01) and RP GS (HR 2.38, 95% CI 1.74-3.28; p<0.01). This association persisted in multivariable models after adjusting for perioperative variables.

CONCLUSIONS: Men with GS 9-10 had higher ACM and PCSM rates compared to those with GS 8. GS 8 and GS 9-10 PC should be considered separately in both the preoperative and postoperative setting as suggested by the new PCGS.

PATIENT SUMMARY: The prostate cancer grading system can predict mortality risk after radical prostatectomy (RP) for men with Gleason score 8-10 disease based on both biopsy and RP Gleason scores. There are significant differences in all-cause mortality and prostate cancer-specific mortality following surgery between men with Gleason score 8 and those with Gleason score 9-10 disease.