Login to Access Video or Poster Abstract: MP20-09
Sources of Funding: none

Introduction

There is much enthusiasm for multi-parametric MRI (mpMRI)-ultrasound fusion biopsy in those with an elevated PSA, a prior negative biopsy or those on active surveillance. However, the predictive value of MRI – targeted biopsy in predicting final cancer grade has not been well addressed. The uncertainties of both over staging and under staging using MRI fusion targeted biopsy have not been well addressed. _x000D_ We aimed to evaluate the accuracy of cancer risk estimation with MRI fusion biopsy; traditional sextant and anterior (14 cores) ultrasound guided biopsy or the combination, using whole-mount histopathology at time of prostatectomy. _x000D_

Methods

We retrospectively analyzed 114 patients who had radical prostatectomy in 2014-2016. All patients had undergone systematic ultrasound guided biopsy and mpMRI fusion biopsy. We compared Gleason Score (GS ≥7) upgrading or downgrading between MRI fusion and systematic ultrasound guided biopsy to that of the final Gleason score evaluated by whole-mount histopathological analysis. Logistic regression was used to evaluate association to adverse pathological outcome for each biopsy approach.

Results

Of 114 patients, GS ≥7 cancer grade found on MRI fusion biopsy matched final pathology in 46% of the cases while it was overestimated in 15% of patients and underestimated in 39%. Cancer found on traditional systematic biopsy matched final pathology in 56% of patients while it overestimated grade in 26% and underestimated grade in 17% of patients with GS≥7. The highest Gleason score from combined MRI fusion and systematic biopsy only underestimated 11% of patients but overestimated grade in 33% of patients who had GS≥7 on their final pathology. In the logistic regression model, having a GS ≥ 3+4 detected on MRI fusion biopsy was associated with higher odds (OR: 3.5 95% CI 1.3-9.3, p <0.01) of higher stage cancer (≥pT3a) at RP. The association persisted when the model was adjusted for clinical CAPRA score. This study was limited by its retrospective nature.

Conclusions

Risk of over - staging using MRI fusion biopsy is low compared to systematic biopsy. However, MRI fusion biopsy alone could significantly underestimate those with clinically significant disease. Using MRI fusion biopsy alone to detect high grade cancer may not be adequate in this contemporary cohort. This data may have important implications for guiding treatment decisions._x000D_ _x000D_

Funding

none