Validation of the Kattan Nomogram for prostate cancer recurrence after radical prostatectomy

Background: The Kattan postoperative radical prostatectomy (RP) nomogram is used to predict biochemical recurrence-free progression (BCRFP) after RP. However, external validation among contemporary patients using modern outcome definitions is limited. Methods: A total of 1,931 patients who underwent RP at Roswell Park Cancer Institute (RPCI) between 1993 and 2014 (median follow-up, 47 months; range, 0-244 months) were assessed for NCCN-defined biochemical failure (BF) and RPCI-defined treatment failure (TF). Actual rates of biochemical failure-free survival (BFS; defined as 1 - BF) and treatment failure-free survival (TFS; defined as 1 - TF) were compared with Kattan BCRFP nomogram predictions. Results: The Kattan BCRFP nomogram predictions at 5 and 10 years were predictive of BFS (area under the receiver operating characteristic curve [AUC], 0.772) and TFS (AUC, 0.774). The Kattan BCRFP nomogram tended to underestimate BFS and TFS compared with actual outcomes. The Kattan 5-year BCRFP predictions consistently overestimated actual 5-year BFS outcomes among subgroups of high- and intermediate-risk patients with at least 5-year outcomes. Conclusions: The Kattan BCRFP nomogram is a robust predictor of NCCN-defined BF in a large sample of patients with RP with substantial follow-up and modern, standardized failure definitions.