Predicting insignificant prostate cancer: Analysis of the pathological outcomes of candidates for active surveillance according to the pre-International Society of Urological Pathology (ISUP) 2014 era versus the post-ISUP2014 era

Objectives: To analyse the pathological outcomes of candidates for active surveillance according to the era before the International Society of Urological Pathology 2014 consensus meeting (in which Gleason pattern 4 was assigned to all cribriform patterns) versus the post-2014 era.

Patients and methods: We retrospectively analysed 118 candidates for active surveillance who underwent radical prostatectomy between 2009 and 2017. We divided our patients into two groups (group 1 [n = 61], operation date 2009–2014; group 2 [n = 57], operation date 2015–2017). The biopsy Gleason grades in group 1 were reviewed to distinguish men with tumours having a cribriform pattern. The postoperative outcomes in the two eras were analysed twice: first, all men in group 1 versus group 2; second, the remaining men after excluding those with cribriform tumours in group 1 versus group 2.

Results: The proportionof men with insignificant prostate cancer was significantly lower in group 1 than in group 2 (36.8% vs. 57.3%, p = 0.040). After excluding 11 men with cribriform tumours from group 1, those remaining (46 men) were compared again with group 2. In this analysis, the proportion of men with insignificant prostate cancer was similar between the two groups (41.3% vs. 57.3%, p = 0.146). In the analysis of men with cribriform tumours, 9 of 11 patients had violated the criteria for insignificant prostate cancer.

Conclusion: Our findings indicate that the accuracy of the active surveillance protocol for predicting insignificant prostate cancer has been affected by the coexistence of cribriform patterns and pure Gleason 6 tumours in the pre-2014 era. We suggest that the current active surveillance protocols need to be modified.