Login to Access Video or Poster Abstract: MP93-20
Sources of Funding: none

Introduction

Tumor contact length (TCL) on multiparametric magnetic resonance imaging (mpMRI), defined as the length of a lesion in contact with the prostatic capsule, is a novel marker with promising early results. We aimed to evaluate TCL as a predictor of pathological extracapsular extension (ECE), and biochemical recurrence (BCR) in patients undergoing robotic-assisted radical prostatectomy (RARP).

Methods

We retrospectively analyzed the records of 230 consecutive patients who underwent prostate mpMRI followed by RARP from April 2013 to July 2016. TCL was measured using T2-weighted magnetic resonance images. Logistic and Cox regression analysis were used to assess associations of clinical, imaging, and histopathological variables with ECE and BCR. Receiver operating characteristic curves were used to characterize and compare TCL performance with biopsy Gleason score (bGS) and Partin tables.

Results

There were 61/230 (26.5%) ECE and 18/230 (7.8%) BCR patients. Patients with adverse pathology/oncologic outcomes had longer TCL compared to those without adverse outcomes (ECE: 16.6 vs. 7.2mm, p<0.0001 and BCR: 13.4 vs. 9.3mm, p=0.0334). On multivariate analysis, TCL and bGS were the independent predictors of ECE (TCL odds ratio: 1.23, p<0.0001 and bGS odds ratio: 1.75, p=0.0202). Cox regression analysis demonstrated both TCL and bGS was significant predictors of BCR (TCL hazard ratio: 1.05, p=0.0423 and bGS hazard ratio: 1.96, p=0.0030). TCL alone was found to have good predictive ability for ECE (AUC: 0.84) and the best TCL thresholds for predicting ECE was 13.5 mm (sensitivity 70%, specificity 86%). Kaplan-Meier survival analysis was used to compare BCR-free survival between patients with TCL less vs. more than 13.5 mm (Fig). Patients with TCL >13.5 mm had significantly poor BCR-free survival compared to patients with TCL ?13.5mm (log-rank test, p=0.0059).

Conclusions

We demonstrate that TCL is an independent predictor of ECE. The longer the TCL, the more biochemical recurrence likely occur.

Funding

none