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BJU Int. 2018 Dec;122(6):1025-1033. doi: 10.1111/bju.14353. Epub 2018 May 14.

Development and internal validation of a side-specific, multiparametric magnetic resonance imaging-based nomogram for the prediction of extracapsular extension of prostate cancer.

Author information

1
Department of Urology, Icahn School of Medicine at Mount Sinai, New York, NY, USA.
2
Department of Urology, Vita-Salute San Raffaele University, Milan, Italy.
3
Department of Radiology, Icahn School of Medicine at Mount Sinai, New York, NY, USA.
4
Department of Pathology, Icahn School of Medicine at Mount Sinai, New York, NY, USA.

Abstract

OBJECTIVES:

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

MATERIALS AND METHODS:

We retrospectively analysed 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: prostate-specific antigen; highest ipsilateral biopsy Gleason grade; highest ipsilateral percentage core involvement; and ECE on multiparametric magnetic resonance imaging (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 'leave-one-out' cross-validation. Calibration was graphically investigated. The decision curve analysis was used to evaluate the net clinical benefit.

RESULTS:

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 predict ECE correctly 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 for inclusion in the nomogram. After internal validation, the area under the curve was 82.11%. The model demonstrated excellent calibration and improved clinical risk prediction, especially when compared with relying on mpMRI prediction of ECE alone. When retrospectively applying the nomogram-derived probability, using a 20% threshold for performing nerve-sparing, nine out of 14 positive surgical margins (PSMs) at the site of ECE resulted above the threshold.

CONCLUSION:

We developed an easy-to-use model for the prediction of side-specific ECE, and hope it serves as a tool for planning nerve-sparing radical prostatectomy and in the reduction of PSM in future series.

KEYWORDS:

#PCSM; #ProstateCancer; extracapsular extension; multiparametric MRI; nerve sparing; positive surgical margins

PMID:
29676063
DOI:
10.1111/bju.14353

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