Multiparametric magnetic resonance imaging (mpMRI) may be useful for characterizing prostate cancer in men receiving neoadjuvant therapy prior to robotic-assisted radical prostatectomy (RARP), according to preliminary findings from a phase 2 study.

In the study, 20 men with intermediate- and high-risk prostate cancer (PCa) underwent mpMRI at baseline and after 6 months of antiandrogen (AA) therapy with enzalutamide and androgen deprivation therapy (ADT) with goserelin.

Before starting AA-ADT, mpMRI indicated bladder or rectal invasion in 2 men (10%), extraprostatic extension (EPE) in 18 (90%), seminal vesical invasion (SVI) in 6 (30%), and organ-confined disease in 1 (5%). After AA-ADT, mpMRI revealed no cases of bladder or rectal invasion and 7 (35%), 5 (25%), and 10 (50%) cases of EPE, SVI, and organ-confined disease, respectively.

Final whole-mount H&E pathology revealed no cases of bladder or rectal invasion, 8 (40%) cases of EPE, 4 (20%) cases of SVI, 9 (45%) of organ-confined disease, and 3 (15%) case in which no evidence of PCa was observed, a team at the National Cancer Institute in Bethesda, Maryland, led by Peter A. Pinto, MD, reported in Urologic Oncology.

According to the investigators, mpMRI following AA-ADT had a positive predictive value (PPV) and negative predictive value (NPV) of 71% and 77%, respectively, for EPE, 80% and 100% for SVI, and 80% and 90% for organ-confined disease.

Post-AA-ADT mpMRI correctly staged disease in 15 cases (75%), with 17 cases (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.

“This study reports our initial experience using mpMRI to assess the effects of antiandrogen and androgen deprivation therapy on PCa staging before surgery in addition to its correlation with final H&E pathology,” Dr Pinto and his collaborators wrote. “In doing so, we provide insight to how urologists, medical oncologists, and radiologist can interpret imaging of AA-ADT-treated prostates to assess whether high-risk patients are candidates for prostatectomy after neoadjuvant therapy.”

At baseline, study patients had a mean age of 66 years and median PSA level prior to AA-ADT of 9.5 ng/mL), and median PSA level after AA-ADT of 0.02 ng/mL. The investigators defined intermediate-risk PCa as a PSA level of 10 to 20 ng/mL, Gleason score of 7, or clinical stage cT2b or cT2c disease. They defined high-risk PCa as a PSA level above 20 ng/mL Gleason score of 8 or higher, or clinical stage cT3a or cT3b. The AA-ADT regimen consisted of 160 mg of enzalutamide daily and goserelin 10.8 mg injection every 12 weeks for 24 weeks prior to RARP.

Reference

Gold SA, VanderWeele DJ, Harmon S, et al. mpMRI preoperative staging in men treated with antiandrogen and androgen deprivation therapy before robotic prostatectomy. Urol Oncol. 2019;

https://doi.org/10.1016/j.urolonc.2019.01.012