Nomograms to predict the pathological stage of clinically localized prostate cancer in Korean men: Comparison with Western predictive tools using decision curve analysis

Objectives: To develop and evaluate nomograms to predict the pathological stage of clinically localized prostate cancer after radical prostatectomy in Korean men. Methods: We reviewed the medical records of 2041 patients who had clinical stages T1cT3a prostate cancer and were treated solely with radical prostatectomy at two hospitals. Logistic regressions were carried out to predict organ-confined disease, extraprostatic extension, seminal vesicle invasion, and lymph node metastasis using preoperative variables and resulting nomograms. Internal validations were assessed using the area under the receiver operating characteristic curve and calibration plot, and then external validations were carried out on 129 patients from another hospital. Head-to-head comparisons with 2007 Partin tables and Cancer of the Prostate Risk Assessment score were carried out using the area under the curve and decision curve analysis. Results: The significant predictors for organ-confined disease and extraprostatic extension were clinical stage, prostate-specific antigen, Gleason score and a percent positive core of biopsy. Significant predictors for seminal vesicle invasion were prostate-specific antigen, Gleason score and percent positive core, and those for lymph node metastasis were prostate-specific antigen and percent positive core. The area under the curve of established nomograms for organ-confined disease, extraprostatic extension, seminal vesicle invasion and lymph node metastasis were 0.809, 0.804, 0.889 and 0.838, respectively. The nomograms were well calibrated and externally validated. These nomograms showed significantly higher accuracies and net benefits than two Western tools in Korean men. Conclusion: This is the first study to have developed and fully validated nomograms to predict the pathological stage of prostate cancer in an Asian population. These nomograms might be more accurate and useful for Korean men than other predictive models developed using Western populations.