mpMRI preoperative staging in men treated with antiandrogen and androgen deprivation therapy before robotic prostatectomy

Abstract

Introduction: Using multiparametric magnetic resonance imaging (mpMRI), we sought to preoperatively characterize prostate cancer (PCa) in the setting of antiandrogen plus androgen deprivation therapy (AA-ADT) prior to robotic-assisted radical prostatectomy (RARP). We present our preliminary findings regarding mpMRI depiction of changes of disease staging features and lesion appearance in treated prostate.

Methods: Prior to RARP, men received 6 months of enzalutamide and goserelin. mpMRI consisting of T2 weighted, b = 2,000 diffusion weighted imaging, apparent diffusion coefficient mapping, and dynamic contrast enhancement sequences was acquired before and after neoadjuvant therapy. Custom MRI-based prostate molds were printed to directly compare mpMRI findings to H&E whole-mount pathology as part of a phase II clinical trial (NCT02430480).

Results: Twenty men underwent imaging and RARP after a regimen of AA-ADT. Positive predictive values for post-AA-ADT mpMRI diagnosis of extraprostatic extension, seminal vesicle invasion, organ-confined disease, and biopsy-confirmed PCa lesions were 71%, 80%, 80%, and 85%, respectively. Post-treatment mpMRI correctly staged disease in 15/20 (75%) cases with 17/20 (85%) correctly identified as organ-confined or not. Of those incorrectly staged, 2 were falsely positive for higher stage features and 1 was falsely negative. Post-AA-ADT T2 weighted sequences best depicted presence of PCa lesions as compared to diffusion weighted imaging and dynamic contrast enhancement sequences.

Conclusion: mpMRI proved reliable in detecting lesion changes after antiandrogen therapy corresponding to PCa pathology. Therefore, mpMRI of treated prostates may be helpful for assessing men for surgical planning and staging.

Keywords: Androgen deprivation; Enzalutamide; Multiparametric MRI; Prostate cancer.

Copyright © 2019. Published by Elsevier Inc.

Figures

Fig. 1.

Changes in PCa staging features detected by mpMRI before and after AA-ADT, then confirmed on post-RARP H&E pathologic analysis.

Fig. 2.

A 61 year-old African American male presented with serum PSA = 17.29 ng/ml. Pretreatment mpMRI (top row) demonstrated a PI-RADSv2 5 lesion in the right apex-mid peripheral zone (arrow) measuring 2.8 cm in greatest axial dimension in the axial T2W MRI, which shows restricted diffusion on ADC map and b2000 DWI with increased vascularity on DCE MRI. The lesion was suspicious for extraprostatic extension. A 12-core TRUS Sbx yielded 2 cores positive for Gleason 8 (4 + 4) cancer and 2 cores positive for Gleason 7 (4 + 3) cancer; MRI-TRUS Tbx detected Gleason 8 (4 + 4) cancer at that lesion. After 6 months of neoadjuvant enzalutamide + ADT, post-treatment mpMRI (middle row) detected no suspicious lesion in any pulse sequence. No evidence of malignancy was seen on postsurgical H&E whole-mount pathology (bottom row).

Fig. 3.

Signal positivity for index lesions on post-treatment mpMRI by pulse sequence and later confirmed as PCa positive or negative on postsurgery pathology. Index lesions defined as lesion with largest axial diameter measured on MRI and/or highest Gleason score (GS) of the lesion from Tbx. DWI = b2000 diffusion weighted imaging. DCE = dynamic contrast enhancement. DCE sequence was not available for 1 patient.