Role of multiparametric magnetic resonance and ultrasound-guided/MR fusion biopsy in patients with low-risk prostate cancer suitable for active surveillance

BACKGROUND: To evaluate the impact of multiparametric magnetic resonance (mpMR) and fusion biopsy in patients with low-risk prostate cancer suitable for active surveillance (AS) in order to reduce cases of disease downstaging. METHODS: Between January 2016 and February 2018, 97 mpMRs were performed in patients with clinical indications for AS; the mpMR results were expressed using the PIRADS (Prostate Imaging Reporting and Data System) v2.1 score. Of the patients with equivocal or suspicious findings (PIRADS ≥3), 26 underwent transrectal ultrasound/MR fusion biopsy; the histological results were analysed and correlated to the MR data. RESULTS: Multiparametric magnetic resonance documented benign findings (i.e. PIRADS 1-2) in 42/97 patients (43.3%) while, in the remaining 55/97 (56.7%), abnormal findings were found: 39/97 (40.2%) PIRADS 3, 14/97 (14.4%) PIRADS 4 and 2/97 (2.1%) PIRADS 5. Twenty-six patients underwent fusion biopsy (17 with PIRADS 3, 7 with PIRADS 4, 2 with PIRADS 5); in 17/26 (65.4%), a Gleason Score ≥7 was found and, in particular, in 10/17 (58.8%) of the PIRADS 3, 5/7 (71.4%) of the PIRADS 4 and 2/2 (100%) of the PIRADS 5. CONCLUSIONS: More than half of the patients in AS showed MR abnormalities and the risk of upstaging increased as the PIRADS score increased; fusion biopsy allowed clarifying the importance of the MR findings, identifying a more aggressive prostate tumour in a high percentage of cases (65.4%). Therefore, MR with fusion biopsy should be proposed for all patients in AS for a correct diagnostic classification.