2208 ACTIVE SURVEILLANCE FOR PROSTATE CANCER: DIAGNOSTIC ACCURACY OF MULTIPARAMETRIC MRI IN SELECTION OF PATIENTS

Abstract

INTRODUCTION AND OBJECTIVES: In case of low risk prostate cancer (PCa), the question arises whether to treat or follow a program of active surveillance (AS). These programs can sometimes mistakenly select patients. Multiparametric MRI (mp-MRI) has shown promise in localizing and characterize PCa. Aim of this study was to evaluate the role of mp-MRI in improving the selection of patients eligible for AS programs. METHODS: We reviewed our prospectively maintained PCa database and extracted the data about consecutive patients treated with radical prostatectomy (RP) previously undergone mp-MRI. We compared data of patients who fulfilled the AS criteria with data of mp-MRI and the pathological analysis. Clinical AS criteria were those of PRIAS (Prostate Cancer Research International: Active Surveillance) protocol: PSA 10 ng/ml and density 0.2 ng/ml; 2 positive cores at prostate biopsy and GS 6; clinical stage T1c-T2. Radiological criteria of inclusion of AS on mp-MRI were major tumor diameter 10 mm, organ-confined PCa, ADC 0.8/1. Pathological criteria using Epstein definition of insignificant disease were: organ-confined PCa, non-evidence of Gleason 4 or 5; tumor volume 0.5 cc. The same surgeon, the same uro-pathologist and the same uro-radiologist performed all the procedures. Sensitivity, specificity, positive and negative predictive value (PPV and NPV) of PRIAS criteria, mp-MRI and PRIAS mp-MRI were calculated based on 2x2 tables, using pathological results as gold standard. RESULTS: On pathological examination, 19/180 (10.6%) patients would have been properly selected for AS. Results are summarized in Table 1. Using PRIAS criteria to select patients for AS, sensitivity, specificity, PPV and NPV were 15.8%, 75.8%, 7.1% and 88.4%, respectively. Using mp-MRI criteria only to select patients for AS, sensitivity, specificity, PPV and NPV were 100%, 87.9%, 50% and 100%, respectively. Using PRIAS mp-MRI criteria, sensitivity, specificity, PPV and NPV were 15.8%, 98.8%, 60% and 90.9%, respectively. Only 2 patients selected for AS with PRIAS and MRI criteria had a non-low risk PCa (GS 7). CONCLUSIONS: Our results suggested that actual inclusion criteria are inadequate to candidate patients with PCa for AS. In our cohort, mp-MRI seems to improve selection of patients for AS when used in combination with clinical criteria.