Multiparametric Magnetic Resonance Imaging Grades the Aggressiveness of Prostate Cancer

SIMPLE SUMMARY: Prostate cancer (PCa) aggressiveness can be assessed from clinical and pathologic surrogate endpoints as the International Society of Uropathology grade group (GG) in prostate biopsies, the type of pathology from surgical specimens, the clinical stage, and the risk of biochemical recurrence after treatment of localised PCa. Low evidence exists about the association between prostate magnetic resonance imaging (MRI) and PCa aggressiveness beyond the known increased risk of clinically significant PCa (csPCa) as Prostate Imaging and Data Report System (PI-RADS) increase. Therefore, we confirm previous data and generate new evidence from all the previous surrogate endpoints of PCa aggressiveness, confirming that MRI grades the aggressiveness of PCa. ABSTRACT: We sought to find further evidence showing the increase in PCa aggressiveness as PI-RADS score increases from four surrogates of PCa aggressiveness: i. prostate biopsy GG (≤3 vs. >3), ii. type of pathology in surgical specimens (favourable vs. unfavourable), iii. clinical stage (localised vs. advanced), and risk of recurrence of localised PCa after primary treatment (low-intermediate vs. high). A group of 692 PCa patients were diagnosed after 3-T multiparametric MRI (mpMRI) and guided and/or systematic biopsies, showing csPCa (GG ≥ 2) in 547 patients (79%) and insignificant PCa (iPCa) in 145 (21%). The csPCa rate increased from 32.4% in PI-RADS < 3 to 95.5% in PI-RADS 5 (p < 0.001). GG ≥ 3 was observed in 7.6% of PCa with PI-RADS < 3 and 32.6% in those with PI-RADS > 3 (p < 0.001). Unfavourable pathology was observed in 38.9% of PCa with PI-RAD < 3 and 68.3% in those with PI-RADS > 3 (p = 0.030). Advanced disease was not observed in PCa with PI-RADS ≤ 3, while it existed in 12.7% of those with PI-RADS > 3 (p < 0.001). High-risk recurrence localised PCa was observed in 9.5% of PCa with PI-RADS < 3 and 35% in those with PI-RADS > 3 (p = 0.001). The PI-RADS score was an independent predictor of all surrogates of PCa aggressiveness as PSA density. We confirmed that mpMRI grades PCa aggressiveness.