San Antonio, Texas USA (UroToday.com) Multiparametric magnetic resonance imaging (mpMRI) is being increasingly utilized in the diagnosis of prostate cancer. The negative predictive value (NPV) of mpMRI for detecting clinically significant prostate cancer (defined as Gleason Grade Group of 3 or higher) is as high as 98% in some series.
With the rise of resistant microorganisms and the nontrivial incidence of post-biopsy sepsis, it is reasonable to question the utility of performing prostate biopsy in patients with mpMRI findings that are not concerning for clinically significant prostate cancer.
The authors examined their prospectively maintained database in a retrospective fashion of all men between January 2012 and December 2015 who underwent mpMRI of the prostate prior to biopsy. Eighty-four total men with a negative mpMRI (PiRADs ≤ 2) were included: 39 biopsy naïve, 30 prior negative biopsy, and 15 active surveillance. All patients underwent a standard transrectal ultrasound guided biopsy. The NPV of negative mpMRI was calculated and a multivariate model was created in an attempt to predict clinically significant cancer on biopsy.
The overall NPV was 86.9% and no significant differences were noted in NPV stratified by clinical scenario (biopsy naïve 89.7%, previous negative biopsy 83.3%, active surveillance 86.7%, p =0.76). Patients with a high likelihood of high grade cancer based on the Prostate Cancer Prevention Trial Risk Calculator (PCPTRC) were more likely to have clinically significant prostate cancer on biopsy in the presence of a negative mpMRI on multivariable analysis (OR 1.01, p < 0.01).
The authors contend that based on these data, it remains necessary to perform biopsy in patients with a negative mpMRI, particularly in those with an elevated PCPTRC estimated risk for high grade cancer. These data on tumors that are “missed” by mpMRI alone are consistent with data from fusion-targeted biopsy series in which routine template biopsy is concomitantly performed. Here, higher grade tumors are found on template biopsy relative to targeted biopsy 15-20% of the time. Thus, template biopsy remains necessary in both negative mpMRI and in the fusion biopsy settings.
Washington University School of Medicine, St Louis, MO
Written By: Benjamin T. Ristau, MD, Society of Urologic Oncology Fellow, Fox Chase Cancer Center
17th Annual Meeting of the Society of Urologic Oncology - November 30 -December 2, 2016 – San Antonio, Texas USA