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

Abstract

BackgroundThe 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. ObjectiveTo 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 participantsOf 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 analysisClinicopathologic 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 limitationsCompared 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. ConclusionsMen 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 summaryThe 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.