Impact of international variation of prostate cancer on a predictive nomogram for biochemical recurrence in clinically localised prostate cancer

Objective: Prostate cancer (PCa) incidence has been rising rapidly in Korea with aggressive clinicopathologic features compared to those observed in Western countries. Our aim was to develop a predictive nomogram for BCR-free survival based on the characteristics of PCa in Korean men and compared its predictive accuracy to an established Western nomogram. Methods: A nationwide multicenter study was designed involving 723 Korean men with clinically localised PCa that had undergone radical prostatectomy. The Cox proportional hazards model was applied to 549 cases from four heavy volume institutions to define prognostic factors and develops the Korean nomogram, which was subjected to internal validation, external validation using a separate cohort of 295 cases, and head-to-head comparison with the updated Kattan nomogram. Results: During the mean follow-up period of 44.8 months, BCR occurred in 251 patients (35.4 %) with aggressive clinicopathologic features. Similar to Western cases, preoperative prostate-specific antigen (PSA), pathologic tumour stage (pT), and Gleason score (GS) were independent prognostic factors and used to develop the Korean nomogram in conjunction with age and surgical margin status. The Korean nomogram performed well for predicting BCR-free 5- and 10-year survival on internal validation. On external validation, the Korean nomogram showed better calibration than the updated Kattan nomogram. Conclusions: Preoperative PSA, pT, and GS were independent prognostic factor for BCR in clinically localised PCa in Korean men. The superior performance of the Korean nomogram for Korean PCa patients suggests that geographic variation in clinicopathologic factors should be considered in a predictive nomogram.