Development and Internal Validation of a Side Specific, Multiparametric MRI-based Nomogram for the Prediction of Extracapsular Extension of Prostate Cancer

To develop a nomogram for predicting side-specific extracapsular extension (ECE) for planning nerve sparing radical prostatectomy (NSRP).

We retrospectively analyzed data from 561 patients who underwent robot-assisted radical prostatectomy between February 2014 and October 2015. To develop a side-specific predictive model, we considered the prostatic lobes separately. Four variables were included: PSA, highest ipsilateral biopsy Gleason grade, highest ipsilateral percentage core involvement and ECE on multiparametric MRI (mpMRI). A multivariable logistic regression analysis was fitted to predict side-specific ECE. A nomogram was built based on the coefficients of the logit function. Internal validation was performed using the leave-one-out cross validation. Calibration was graphically investigated. The DCA was used to evaluate the net clinical benefit.

the study population consisted of 829 side-specific cases, after excluding negative biopsy observations (n=293). ECE was reported on mpMRI and final pathology in 115 (14%) and 142 (17.1%) cases, respectively. Among these, mpMRI was able to correctly predict ECE in 57 (40.1%) cases. All variables in the model except highest percentage core involvement were predictors of ECE (all p≤0.006). All variables were considered to build a nomogram. After internal validation, the AUC was 82.11%. The model demonstrated excellent calibration and improved clinical risk prediction, especially when compared to relying on mpMRI prediction of ECE alone. When retrospectively applying the nomogram-derived probability, using a 20% cutoff for performing NS, nine out of 14 positive surgical margins (PSM) at the site of ECE resulted above the cutoff.

we developed an easy-to-use model for the prediction of side-specific ECE, and hope it serves as a tool for planning NSRP and in the reduction of PSM in future series. This article is protected by copyright. All rights reserved.

BJU international. 2018 Apr 19 [Epub ahead of print]

Alberto Martini, Akriti Gupta, Sara C Lewis, Shivaram Cumarasamy, Kenneth G Haines, Alberto Briganti, Francesco Montorsi, Ash K Tewari

Department of Urology, Icahn School of Medicine at Mount Sinai, New York, USA., Department of Radiology, Icahn School of Medicine at Mount Sinai, New York, USA., Department of Pathology, Icahn School of Medicine at Mount Sinai, New York, USA., Department of Urology, Vita-Salute San Raffaele University, Milan, IT.