Critical assessment of tools to predict clinically insignificant prostate cancer at radical prostatectomy in contemporary men

BACKGROUND. Overtreatment of prostate cancer (PCa) is a concern, especial;u patients who might quality for the diagnosis of insignificant prostate cancer (IPCa). The ability to identify IPCa prior to definitive therapy was tested. METHODS. In a cohort of 1132 men a nomogram was developed to predict the probability of IPCa. Predictors consisted of prostate-specific antigen (PSA), clinical stage, biopsy Gleason sum, core cancer length and percentage of positive biopsy cores (percent positive cores). IPCa was defined as organ-confined PCa (OC) With tumor volume (TV) < 0.5 cc and without Gleason 4 or 5 patterns. Finally, an external validation of the most accurate IPCa nomogram was performed in the same group. RESULTS. IPCa was pathologically confirmed in 65 (5.7%) trien. The 200 bootstrap-corrected predictive accuracy of the new nomogram Was 90% versus 81% for the older nomogram. However, in cutoff-based analyses of patients who were qualified by our and the older nomgrams as high probability for IPCa, respectively 63% and 45% harbored aggressive PCa variants at radical prostatectomy (Gleason score 7-10, ECE, SVI, and/or LNI). CONCLUSIONS. Despite a high accuracy, currently available models for prediction of IPCa are incorrect in 10% to 20% of predictions. The rate of misclassification is even further inflated when specific Cutoffs are used. As a CONCLUSIONS. extreme caution is advised when statistical tools are Used to assign the diagnosis of IPCa