New frontiers ahead focal therapy postoperative follow-up: What is the real role of MRI in this setting?

Abstract

e539 Background: Magnetic resonance imaging (MRI) plays an important role as a treatment-monitoring tool along focal therapy (FT) follow-up. This is the first study to assess MRI ability to correctly predict prostate cancer (PCa) local T-stage in the FT postoperative scenario. We aimed to describe MRI effectiveness in predicting upstaging in two groups of men: 1) men who failure after primary FT and then underwent salvage robotic-assisted radical prostatectomy (S-RARP) and 2) men who underwent RARP as primary treatment (P-RARP). Methods: Prospective data of 2775 men underwent RARP for localized PCa from 2000 to 2016 were reviewed. Twenty-two men underwent S-RARP after FT failure (S-RARP group). Total 2750 underwent RARP as first treatment. Matched-pair 1:2 selection of 44 out of 2750 patients by age defined primary RARP group (P-RARP). All patients underwent MRI immediately before RARP. MRI findings were confronted with final surgical pathology. Primary endpoint: sensitivity, specificity, positive and negative predictive values; positive (+LR) and negative (-LR) likelihood ratio regarding upstaging analysis on S-RARP. Secondary endpoint: same effectiveness analysis on P-RARP. Results: Preoperative MRI failed in predicting upstaging in 80% versus 91.7% of patients (p = 0.515) that presented final pathological status ≥ pT3a on S-RARP and P-RARP groups, respectively. On the other hand, when final pathology described a localized disease T2a-T2c, MRI correctly predicted the final pathological status in 81.8% versus 95.2% of patients (p = 0.27) on S-RARP and P-RARP groups, respectively. Between-group analysis, showed sensitivity and specificity rates of 20% versus 8.33% and 81.8% versus 95.23%, respectively; Positive and negative predictive values of 33.33% versus 50% and 69.23% versus 64.51%, respectively; Positive (+LR) and negative (-LR) likelihood ratio of 1.1 versus 1.74 and 0.98 versus 0.96, respectively. Conclusions: MRI has shown to be a weak diagnostic tool for predicting extra-prostatic disease along FT follow-up. Urologists may be warned about the risk of underdiagnosis and undertreatment in patients presenting failure after FT.