Introduction

Some authors proposed the possibility to avoid follow-up biopsies when multiparametric-magnetic resonance (mpMRI) is not suspicious for clinically significant prostate cancer (csPCa) in patients on active surveillance (AS)

Methods

Between 2009 and 2016, 235 patients were included to AS program for low risk PCa according to the PRIAS criteria. 95 underwent a mpMRI and represent the study population. Number, size, location and grading of mpMRI lesions were recorded. We compared pathologic outcomes in patients submitted to targeted biopsies. csPCa was defined as Gleason score >6. We analyzed the mpMRI performed in patients on AS and correlated mpMRI findings to histopathological results of subsequent biopsies. The rates of csPCa was assessed in patients submitted to prostate biopsy after mpMRI according to PIRADS score, for the biopsy approach (targeted vs. systematic)

Results

80 patients underwent more than one mpMRI, resulting in 120 evaluable mpMRI. Median time from protocol entry to mpMRI was 12 months. Overall, 48 (40.0%) and 72 (60.0%) patients had a PIRADS score ≤2 and ≥3, respectively. PIRADS score was 3 in 32 (44.4%), 4 in 31 (43.1%), and 5 in 9 (12.5%) patients. Median and mean lesion size at MRI were 9 and 9.1 mm. 34 (35%) suspicious lesions were localized at the transitional zone of the prostate, while 23 (23.7%), 9 (13.5%), and 27 (27.8%) at the apex, the base and the lateral zone. 18 patients (18.9%) had >1 suspicious lesion. Overall, 75 patients underwent a biopsy after mpMRI, 34 (45.4%) with a targeted approach and 41 (54.6%) with random systematic biopsies. Of 75 patients, 54 (72.5%) had PIRADS ≥3 while the others (n=21) had PIRADS ≤2. Of 54 patients with PIRADS ≥3, 17 (31.4%) had Gleason ≥7. However, patients with PIRADS ≥3 submitted to targeted biopsy (n=34), Gleason 7 or higher was found in 23 (67.6%) vs. 7 (33.3%) in patients with PIRADS score ≥3 submitted to systematic biopsies (p=0.001). Of patients submitted to targeted biopsy (n=34), Gleason ≥7 outside of the targeted area was found in 7 patients (20.1%). Finally, of 21 patients with PIRADS ≤2, 7 (33.3%), 11 (52,3%) and 3 (14.5%) had negative biopsy, Gleason 6 and Gleason ≥7 at systematic biopsy. These figures resulted in 3+7/75 (13%) patients with csPCa that were missed by mpMRI

Conclusions

80% of AS patients submitted to mpMRI have suspicious csPCa, especially in areas not normally investigated by means of random biopsies. Therefore, mpMRI should be taken into account when evaluating candidates for AS. However, 13% of clinically significant cancers may be missed by mpMRI

Funding

none