Evaluation of the 2015 Gleason Grade Groups in a Nationwide Population-based Cohort

Abstract

BackgroundNew five-tiered Gleason grade groups (GGGs) were recently proposed, in which Gleason 6 is GGG 1, Gleason 3+4 is GGG 2, Gleason 4+3 is GGG 3, Gleason 8 is GGG 4, and Gleason 9-10 is GGG 5. ObjectiveTo examine the performance of the new GGGs in men with prostate cancer from a nationwide population-based cohort. Design, setting, and participantsFrom the National Prostate Cancer Register of Sweden, we identified 5880 men diagnosed with prostate cancer from 2005 to 2007, including 4325 who had radical prostatectomy and 1555 treated with radiation therapy. Outcome measurements and statistical analysisKaplan–Meier survival analysis, Cox proportional hazards models, and concordance indices were used to examine the relationship between the GGGs and biochemical recurrence after radical prostatectomy and radiation therapy. Results and limitationsAmong men treated with surgery, the 4-yr biochemical recurrence-free survival rates were 89%, 82%, 74%, 77%, and 49% for GGG 1–5 on biopsy, and 92%, 85%, 73%, 63%, and 51% based on prostatectomy GGG, respectively. For men treated by radiation therapy, men with biopsy GGG of 1–5 had 4-yr biochemical recurrence-free survival rates of 95%, 91%, 85%, 78%, and 70%. Adjusting for preoperative serum prostate-specific antigen and clinical stage, biopsy GGGs were significant independent predictors of biochemical recurrence after radical prostatectomy and radiation therapy. The new 5-tier system resulted in virtually no change in predictive accuracy compared with the current 3- and 4-tier classifications. Limitations include a median follow-up of 4.6 yr, precluding the ability to examine long-term oncologic outcomes. ConclusionsThe newly proposed GGGs offer a simplified, user-friendly nomenclature to aid in patient counseling, with similar predictive accuracy in a population-based setting to previous classifications. Patient summaryThe new Gleason grade groups, ranging from 1–5, provide a simplified, user-friendly classification system to predict the risk of recurrence after prostatectomy and radiation therapy.