SIU 2017: Correlation of mpMRI Contours with 3-Dimensional 5mm Transperineal Prostate Mapping Biopsy within the PROMIS Trial Pilot: What Margins Are Required?

Lisbon, Portugal ( It is known that mpMRI offers the possibility to locate cancer in a three dimensional space and aid surgical planning. In this study the authors investigated the margin needed around an mpMRI lesion for complete disease control in a prospectively enrolled biopsy naive population, who underwent mpMRI followed by Transperineal Prostate Mapping with biopsies taken every 5mm (5TPM).

94 patients included in this analysis were part of the pilot phase of Prostate MRI Imaging Study (NCT01292291) investigating accuracy of mpMRI against standard of care with TPM as a reference test. All patients were biopsy-naive with a PSA below 15ng/ml. All patients underwent 1.5T mpMRI with a standardized protocol (T2W, Diffusion, DCE), and blinded reported using Likert scoring. Each core was separately labelled and oriented in space. Each prostate and MRI lesion was contoured on T2W-imaging, blinded to pathology. A 3D digital map of the TPM was reconstructed using an in-house software. Correlation between mpMRI and biopsy findings was automatically carried out using a platform generating the registration based on landmarks. The margin around the MRI lesion was reported as the maximum distance within a set of negative biopsy locations surrounding the MRI lesion. Results were also stratified by MRI score, Gleason Score, lesion eligibility to focal therapy and significance.

In total, 41 patients (median PSA 6.5ng/ ml, median age 62) were found to harbor cancer at 5TPM in this cohort, yielding 75 MRI lesions that corresponded to cancer at 5TPM. The median number of MRI lesions per patient was 1.5. As a control of registration, correlation between MRI volume and TPM volume was I =0.92 (p<0.001). The mean margin (enclosing a perimeter of negative cores) for MRI lesions corresponding the cancer at 5TPM was 7.0 mm (SD 4.6mm). For lesions eligible for focal therapy (n= 35), the mean margin was 7.3 (SD 4.3mm). The mean Gleason score of biopsy core outside the MRI lesion was 6.7 (+/- 0.5).

In this elegant study, the authors were the first to report a margin around an mpMRI lesion when based on prostates that have not been removed surgically, and evaluated against a very accurate 3-dimensional 5mm mapping biopsy. These findings have significant implications for focal therapy and nerve-sparing surgery.

Presented by: Orczyk Clio
Affiliation: University College London, London, United Kingdom

Written by: Hanan Goldberg, MD, Urologic Oncology Fellow (SUO), University of Toronto, Princess Margaret Cancer Centre.Twitter: @GoldbergHanan at the 37th Congress of Société Internationale d’Urologie - October 19-22, 2017- Lisbon, Portugal