INTRODUCTION AND OBJECTIVE:
Recently, micro-ultrasound (microUS) has been proposed as an alternative to multiparametric magnetic resonance imaging for the diagnosis of clinically significant Prostate Cancer (PCa), but its role in the local staging of PCa has not been determined yet. Our aim was to evaluate the accuracy of microUS in predicting extraprostatic extension (EPE) of PCa prior to surgery.
This is a single-institutional prospective cohort study. Patients with biopsy-proven PCa scheduled for robot-assisted radical prostatectomy (RARP) were recruited. Patients with PSA>20ng/mL and a prostate volume>100 mL, were excluded. All patients underwent microUS before RARP. The following ultrasound features were evaluated as predictors of non-organ-confined disease: curvilinear contact length(CCL), capsular bulging, visible breach of the prostate capsule(visible extracapsular extension; ECE), presence of hypoechoic halo or ring, and obliteration of the vesicle-prostatic angle. The ability of each feature to predict EPE was determined. Multivariable logistic regression models (LRMs) were fitted to test the predictors of EPE, and their accuracy estimated with the area under the ROC-curve (AUC) analysis. The diagnostic performance of the most accurate predictor was tested.
Overall, 140 patients were recruited. Besides CCL, all predictors were associated with non-organ-confined disease (p<0.001). Final pathology showed that 79 (56.4%) and 61(43.3%) had respectively a pT2 and a pT3 or greater disease. Rate of non-organ-confined disease increased from 44% in those individuals with only 1 predictor (OR 7.71, 95% CI 1.63-13.60), to 92.3% in those where 4 predictors were simultaneously observed (OR 72.00, 95% CI 8.31-623.44). At MLRM, the most significant risk factors for EPE were visible ECE (OR 9.66; 95%CI 3.64–25.66; p<0.0001), positive digital rectal examination (OR 3.43; 95%CI 1.33–8.89; p=0.011) and capsular bulge (OR 3.28, 95%CI 1.26–8.54, p=0.015). Presence of ECE at microUS predicted EPE with a sensitivity of 72.1% and a specificity of 88%, a negative predictive value of 80.5% and positive predictive value of 83.0%.
Our findings suggest that microUS may represent an accurate tool for the evaluation of non-organ confined PCa.
Source of Funding: