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Abstract

OBJECTIVE: To assess the relationship between the ISUP 2014 grading system, biochemical relapse (BCR) and clinical relapse (CLR) following radical prostatectomy, to determine whether the 2014 ISUP grading system is a better predictor of survival compared to the previous Gleason scoring systems, and to investigate whether incorporation of the tertiary pattern/grade into the ISUP scoring system significantly improves its efficacy. PATIENTS AND METHODS: 635 radical prostatectomy cases (1991-1999) were identified from a database at a single institution. A histopathology review was performed to re-grade the cases as per the ISUP 2014 grading system. All relevant clinicopathological data and clinical follow up (median 15.25 years, 0.3-26 years) were obtained. Log rank, Kaplan Meier, Cox regression and Harrell's concordance c-indices analyses were performed. RESULTS: At a median follow up of 15 years, 276 (44%) of patients had BCR and 41 (7%) had clinical relapse. Grade Groups 1, 2, 3, 4 and 5 were seen in 112 (18%), 307 (48%), 129 (20%), 33 (5%) and 54 (9%) patients respectively: 337 (53%) were upgraded, while 70 (11%) were downgraded compared to the 1992 Gleason system. Grade Group (HR: 4.9, p<0.0001) and pre-operative PSA (HR: 1.4, p<0.001) were independent predictors of BCR. Only Grade Group 5 (HR: 12.3, p=0.02), pre-operative PSA (HR: 1.6, p<0.0001), stage pT3b (HR: 3.1, p=0.03) and pT4 (HR: 12.4, p <0.0001) independently predicted CLR. Harrell's C-indices demonstrate that the 2014 ISUP grading system is significantly better predictor of BCR and CLR as well as prostate cancer specific death, compared to the 2005 ISUP modified Gleason system. The replacement of secondary pattern by the tertiary pattern did not alter the prognostic efficacy of the ISUP 2014 grading system. CONCLUSIONS: The ISUP 2014 grading system is a significant independent predictor of both biochemical and clinical relapse, out-performing the 2005 ISUP modified Gleason system. This classification system has the potential to impact clinical decision-making following radical prostatectomy. This article is protected by copyright. All rights reserved.