Development and validation of a novel risk score for the detection of insignificant prostate cancer in unscreened patient cohorts

BACKGROUND: Active surveillance is recommended for insignificant prostate cancer (PCa). Tools exist to identify suitable candidates using clinical variables. We aimed to develop and validate a novel risk score (NRS) predicting which patients are harbouring insignificant PCa. METHODS: We used prospectively collected data from 8040 consecutive unscreened patients who underwent radical prostatectomy between 2006 and 2016. Of these, data from 2799 patients with Gleason 3 + 3 on biopsy were used to develop a multivariate model predicting the presence of insignificant PC at radical prostatectomy (ERSPC updated definition(3): Gleason 3 + 3 only, index tumour volume < 1.3 cm(3) and total tumour volume < 2.5 cm(3)). This was used to develop a novel risk score (NRS) which was validated in an equivalent independent cohort (n = 441). We compared the accuracy of existing predictive tools and the NRS in these cohorts. RESULTS: The NRS (incorporating PSA, prostate volume, age, clinical T Stage, percent and number of positive biopsy cores) outperformed pre-existing predictive tools in derivation and validation cohorts (AUC 0.755 and 0.76, respectively). Selection bias due to analysis of a surgical cohort is acknowledged. CONCLUSIONS: The advantage of the NRS is that it can be tailored to patient characteristics and may prove to be valuable tool in clinical decision-making.