EAU 2018: The role of multi-parametric MRI as triage test: A propensity-matched comparison of a MRI-triage and a TRUS-biopsy pathway

Copenhagen, Denmark (UroToday.com) Multi-parametric MRI (mpMRI) has high sensitivity and negative predictive value in detecting clinically significant cancer. Dr. Eldred-Evans presented their team’s results of a propensity-matched comparison of a MRI-triage and TRUS-biopsy pathway. In their practice, they introduced a mpMRI triage pathway with a parallel evaluation program to assess the impact of mpMRI as a triage test. The objective of the study was to compare outcomes of the new mpMRI-triage pathway with a matched cohort from the previous TRUS-biopsy pathway.

For this study, a matched-pair analysis of biopsy-naïve men who were referred with a clinical suspicion of prostate cancer and underwent two different diagnostic pathways:

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For the mpMRI triage pathway, transperineal targeted and systematic biopsies were performed with the majority under local anesthetic with sedation. For the standard diagnostic pathway using TRUS-biopsy without a pre-biopsy MRI, men were included if the referral PSA was ≤10 and clinical stage ≤T2. A propensity-matched analysis was conducted with a 1:1 ratio using known prognostic variables including age, family history, PSA and DRE. The demographics and histological outcomes were compared between the triage MRI group and propensity matched control group.

In total, 210 biopsy-naïve patients referred with a suspicion of prostate cancer were matched for inclusion in the study. The two groups did not differ in their baseline characteristics after propensity score matching (all p-values >0.6). The mpMRI triage pathway had a significantly lower biopsy rate of 60% (p<0.0001). The detection rate of clinically significant cancer for each group:

Detection rates of clinically significant disease across a range of definition thresholds

TRUS-biopsy pathway Triage mpMRI Pathway p-value
UCL/Ahmed Definition 1
(any Gleason pattern ≥4+3 or ≥6mm of Gleason 3+3) 13.3% 25.5% <0.0001
UCL/Ahmed Definition 2
(any Gleason pattern ≥3+4 or ≥4mm of Gleason 3+3) 24.8% 29.4% 0.032
Gleason ≥3+4 22.8% 27.5% 0.027
Gleason ≥4+3 5.7% 14.7% <0.0001

The detection of Gleason 3+3 was lower in the mpMRI triage group (2.8% vs. 12.3%, p = 0.012). The average number of biopsy cores in each group was not significantly different (13.4 vs. 12.1, p=0.62).

The authors concluded that the use of mpMRI as a triage test has resulted in a 40% reduction in the number of men biopsied. The mpMRI-triage pathway has reduced the over-diagnosis of insignificant disease and increased the detection of significant disease across a broad range of definitions for clinical significance. There was no significant increase in histological burden with a targeted transperineal approach under local anesthetic. However, the authors caution that medium to long-term follow-up of men not biopsied in the new pathway will be required.

Speaker: David Eldred-Evans, Imperial College London, London, United Kingdom

Co-Authors: Brittain J, Servian P, Miah S, Tam H, Ahmed H, Winkler M

Written by: Zachary Klaassen, MD, Urologic Oncology Fellow, University of Toronto, Princess Margaret Cancer Centre, Twitter: @zklaassen_md, at the 2018 European Association of Urology Meeting EAU18, 16-20 March, 2018 Copenhagen, Denmark
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