Utility of positive core number on MRI‐ultrasound fusion targeted biopsy in combination with PI‐RADS scores for predicting unexpected extracapsular extension of clinically localized prostate cancer

Abstract

ObjectivesTo evaluate the utility of magnetic resonance imaging (MRI) and MRI‐ultrasound fusion targeted biopsy (TB) for predicting unexpected extracapsular extension (ECE) in clinically localized prostate cancer (CLPC).MethodsThis study enrolled 89 prostate cancer patients with one or more lesions showing a Prostate Imaging‐Reporting and Data System (PI‐RADS) score ≥3 but without morphological abnormality in the prostatic capsule on pre‐biopsy MRI. All patients underwent TB and systematic biopsy followed by radical prostatectomy (RP). Each lesion was examined by 3‐core TB, taking cores from each third of the lesion. The preoperative variables predictive of ECE were explored by referring to RP specimens in the lesion‐based analysis.ResultsOverall, 186 lesions, including 81 (43.5%), 73 (39.2%), and 32 (17.2%) with PI‐RADS 3, 4, and 5, respectively, were analyzed. One hundred and twenty‐two lesions (65.6%) were diagnosed as cancer on TB, and ECE was identified in 33 (17.7%) on the RP specimens. The positive TB core number was ≤2 in 129 lesions (69.4%) and three in 57 lesions (30.6%). On the multivariate analysis, PI‐RADS ≥4 (p = 0.049, odds ratio [OR] = 2.39) and three positive cores on TB (p = 0.005, OR = 3.07) were independent predictors of ECE. Lesions with PI‐RADS ≥4 and a positive TB core number of 3 had a significantly higher rate of ECE than those with PI‐RADS 3 and a positive TB core number ≤2 (37.5% vs. 7.8%, p < 0.001).ConclusionsPositive TB core number in combination with PI‐RADS scores is helpful to predict unexpected ECE in CLPC.