Login to Access Video or Poster Abstract: MP20-12
Sources of Funding: none

Introduction

Tumor contact length (TCL) is defined as the amount of prostate cancer in contact with the prostatic capsule. We evaluated the ability of magnetic resonance imaging (MRI) determined tumor contact length to predict pathological extracapsular extension (pECE) compared to existing predictors of pECE.

Methods

We retrospectively analyzed the records of 128 consecutive patients with MRI/ultrasound fusion targeted, biopsy proven prostate cancer who underwent robotic-assisted radical prostatectomy from April 2013 to July 2016. Median patient age was 67 years and median prostate specific antigen was 7.11 ng/ml. Clinical stage was cT1 in 71 cases (55%) and cT2 in 53 (41%). Postoperative pathological analysis confirmed pT2 in 90 patients (70%) and pT3 in 38 (30%). We evaluated 1) in the radical prostatectomy specimen the correlation of pECE with pathological cancer volume, pathological TCL and Gleason score, 2) the correlation between pECE and MRI determined TCL, and 3) the ability of preoperative variables to predict pECE.

Results

Logistic regression analysis revealed that pathological TCL correlated better with pECE than the predictive power of pathological cancer volume (0.822 vs 0.659). The Spearman correlation between pathological and MRI determined TCL was r = 0.873 (p <0.0001). ROC AUC analysis revealed that m MRI determined TCL outperformed cancer core involvement on targeted biopsy and the Partin tables to predict pECE (0.84 vs 0.70 and 0.57, respectively). The best TCL thresholds for predicting pECE was 13.5 mm (sensitivity 71%, specificity 80%) and the predictability of pECE outperformed comparing with conventional MRI criteria (MRI-TCL: odds ratio of 10.0, p<0.0001, and MRI criteria: odds ratio of 1.15, p=0.8670).

Conclusions

MRI determined TCL could be a promising quantitative predictor of pECE. The best TCL threshold of 13.5mm might predict pECE with higher accuracy, although PI-RADSv2 reported tumor-capsule interface of greater than 1.0 cm as cut-off value for staging of pECE.

Funding

none