Background: The rate of insignificant prostate cancer (IPCa) is increasing.
Objectives: To examine three end points in patients with a single, positive core and no high-grade prostate cancer (PCa) at biopsy, namely (1) rate of clinical IPCa at radical prostatectomy (RP), defined as organ-confined PCa with a Gleason score of 6 or lower and tumor volume<0.5 cc; (2) rate of pathologically unfavorable PCa at RP (Gleason 7-10 or non-organ-confined disease); and (3) ability to predict either insignificant or unfavorable PCa at RP.
Design, setting, and participants: Retrospective analysis of 209 men with one positive biopsy core showing Gleason 6 or lower.
Measurements: : Detailed clinical and RP data were used in multivariable logistic regression models. Their bias-corrected accuracy estimates were quantified using the area under the curve (AUC) method.
Results and limitations: At RP, IPCa was present in 28 patients (13.4%) and pathologically unfavorable PCa, defined as Gleason 7 or higher or non-organ-confined PCa, was reported in 70 (33.5%) of 209 men; when Gleason 8 or higher or non-organ-confined PCa was considered, the proportion fell to 11%. Our multivariable models predicting different categories of pathologically unfavorable PCa at RP had an accuracy rate between 56% and 68% for predicting IPCa at RP versus 65.1% to 66.1% and 61.7% for the IPCa nomograms of Kattan et al and Nakanishi et al, respectively. Our data are not applicable to screening because they originate from a referral population.
Conclusions: Despite highly favorable biopsy features, between 11% and 33% of men had unfavorable PCa at RP and only a minority (13.4%) had pathologically confirmed IPCa. Neither clinically insignificant nor pathologically unfavorable features could be predicted with sufficient accuracy for clinical decision making.