Does the introduction of prostate multiparametric MRI into active surveillance of localised prostate cancer improve patient re-classification?

Objectives To determine whether replacement of protocol‐driven repeat prostate biopsy (PB) with multiparametric magnetic resonance imaging (mpMRI) +/‐ targeted repeat prostate biopsy (TB) in evaluating men on active surveillance (AS) for low‐volume low‐ to intermediate‐risk prostate cancer (PCa) altered the likelihood or time to treatment, or reduced the number of repeat biopsies required to trigger treatment. Patients and methods 445 patients underwent AS from 2010‐2016 at our institution with median follow‐up of 2.4 (interquartile range IQR 1.2‐3.7) years. Patients followed a “pre‐2014″ AS protocol up to 2014, which incorporated PB, and following the 2014 NICE guidelines patients followed a “2014‐present” AS protocol including mpMRI. We identified four groups of patients within the cohort (“no mpMRI and no PB”, “PB alone”, “mpMRI +/‐ TB” and “PB and mpMRI +/‐ TB”). Kaplan‐Meier plots and log‐rank tests were used to compare groups. Results 132 of 445 (30%) patients came off AS and underwent treatment intervention, with a median (IQR) time to treatment of 1.55 (IQR 0.71‐2.4) years. The commonest trigger for treatment was PCa upgrading following mpMRI and TB (43 of 132 patients, 29%). No significant difference was observed in the time at which men receiving a PB alone or receiving mpMRI +/‐ TB came off AS to undergo treatment (median 1.9 versus 1.33 years, p=0.7471). Considering only men undergoing repeat biopsy, a greater proportion of individuals receiving post‐mpMRI TB came off AS compared with PB alone (29/66, 44% versus 32/87, 37%, p=0.0033). A single set of repeat biopsies was on average needed to trigger treatment regardless of whether this was a PB or TB. Conclusions Replacing a systematic PB with an mpMRI+/‐TB as part of an AS protocol increased the likelihood of re‐classifying patients on AS and identifying men with clinically significant disease requiring treatment. mpMRI+/‐TB as part of AS thereby represents a significant advance in the oncological safety of the AS protocol.