Background: The objectives of this study were to investigate the discrepancy of Gleason score (GS) between biopsy pathology and radical prostatectomy (RP) specimens and to determine the predictors followed by constructing a nomogram for Gleason sum upgrade (GSU). Methods: We retrospectively reviewed our prospectively maintained prostate cancer (PCa) database. 166 patients who underwent RP following biopsy from October 2012 to September 2019 were enrolled after selection. Univariate and

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... ate logistic regression were sequentially performed to determine the independent predictors. Nomogram was constructed based on independent predictors and receiver operating curve was undertaken to estimate the discrimination. Calibration curve was carried out to assess the concordance between predictive probabilities and true risks. Results: GS concordance rate was 40.4%, whilst GSU was 43.4%. There exists no statistical significance in distribution between global GS and highest GS. The independent predictors are PSA (prostate specific antigen), GPC (greatest percentage of cancer), clinical T-stage and PI-RADS (Prostate Imaging Reporting and Data System) score in the multivariate model. Our model showed good discrimination performance (area under the curve, 0.714). Our developed nomogram was validated internally with good calibration. The model underestimated the risk at the probability range 52-68% and below 28%. The overestimate risk was at the range 29-51% and above 69%. Conclusions: Utilization of basic clinical variables (PSA and T-stage) combined with imaging variable (PI-RADS score) and pathological variable (GPC) increases the predictive accuracy of GSU nomogram improves performance in predicting actual probabilities. From a clinical standpoint, our new nomogram may provide urologists a tool for assessing the risk and making treatment decision for PCa patients.