ORLANDO, FL USA (UroToday.com) - Several studies have shown that multi-parametric MRI (mpMRI) can more accurately identify tumor burden when compared to sextant biopsy protocols. Its performance in detecting all significant foci and impact on biopsy protocols was an area of active investigation and discussion for this year's AUA annual meeting. In this study, presented by Dr. Rick Popert from Guy's Hospital, the ability of mpMRI to exclude clinically significant prostate cancer outside of the index suspicious lesion was evaluated.
They included 104 suspicious lesions identified by mpMRI in a paired cohort study. These lesions were identified by a uro-radiologist who scored each based on PI-RADS (1-5) based on European Consensus guidelines. Subsequently, an MRI-US fusion biopsy was performed, with focal cores taken from the index lesion, and an additional set of cores taken systematically from the rest of the prostate, with each lesion recorded based on its prostate quadrant.
Overall, clinically significant prostate cancer (Gleason Score ≥ 3+4 or maximum cancer core length ≥ 4 mm) was found in 41/104 prostates outside of the mpMRI-identified lesion. Upgrading of the Gleason score occurred in 16% of cases. The location of these foci that were not apparent on mpMRI were in the same quadrant as the mpMRI-identified lesion 9% of the time, otherwise they were in an adjoining quadrant 22% of the time "and in a non-adjoining quadrant in 9%." They noted that the detection rate of clinically significant cacner increased with increasing PI-RADS score. Their overall cancer detection rate was 68% when combining mpMRI fusion-guided biopsy and systematic transperineal biopsy.
From these data, they concluded that, especially in PI-RADS 4 and 5 lesions, mpMRI-guided prostate biopsies allow for good detection rates. They cautioned that, due to the significant amount of "MRI-invisible" cancer, systematic biopsies remain an important practice as sampling the radiologically-identified lesion alone would miss clinically significant cancer foci. Thus, while mpMRI can improve performance of biopsy protocols, it may not mitigate the need to perform systematic diagnostic biopsies.
Presented by Rick Popert, MS FRCS (Urol) at the American Urological Association (AUA) Annual Meeting - May 16 - 21, 2014 - Orlando, Florida USA
Guy's Hospital, London, UK
Written by Martin Hofmann, MD, University of California (Irvine), and medical writer for UroToday.com