Predicting biochemical recurrence and prostate cancer specific mortality after radical prostatectomy: comparison of six prediction models in a cohort of screen and clinically detected prostate cancer patients.

To perform a comparison and external validation of three models predicting biochemical recurrence (BCR) and three models predicting prostate cancer specific mortality (PCSM) in a screening setting, i. e., patients with a screen detected prostate cancer (S-PCa) and in patients with a clinically detected (C-)PCa.

We retrospectively evaluated 795 men with S-PCa (ERSPC Rotterdam) and 1123 men with C-PCa initially treated with RP. Discriminative ability of the models was assessed with the area under the curve (AUC) of the receiver operating characteristics curve, and calibration was assessed graphically using calibration plots.

Median follow-up for S-PCa was 10.4 (interquartile range, IQR, 6.8 - 14.3) and for C-PCa 8.8 (IQR 4.8 - 12.9) years. A total of 123 (15%) men with S-PCa and 389 (35%) men with C-PCa experienced BCR. Of the men with S-PCa and BCR, 24 (20%) died of PCa and 29 died (23%) of other causes. Of the men with C-PCa and BCR, 68 (17%) died of PCa and 105 died (27%) of other causes. The discrimination of the models predicting BCR or PCSM was higher for men with S-PCa (BCR, AUC 0.77 - 0.84, PCSM 0.60 - 0.77) than for the men with C-PCa (BCR 0.75 - 0.79, PCSM 0.51 - 0.68), due to similar patient characteristics of men with S-PCa and the cohorts used to develop these models. The risk of BCR was typically overestimated while the risk of PCSM was typically underestimated.

Prediction models for BCR showed good discrimination and reasonable calibration for both men with S-PCa and men with C-PCa, and even better discrimination for men with S-PCa. For PCSM, the evaluated models are not applicable in both settings of this Dutch cohort due to substantial miscalibration. This warrants caution when using these models to communicate future risks in one's own clinical setting. This article is protected by copyright. All rights reserved.

BJU international. 2019 May 04 [Epub ahead of print]

Sebastiaan Remmers, Jan F M Verbeek, Daan Nieboer, Theo van der Kwast, Monique J Roobol

Department of Urology, Erasmus University Medical Center Rotterdam, The Netherlands., Department of Pathology, Erasmus University Medical Center, Rotterdam, The Netherlands.