San Diego, California (UroToday.com): In today’s International Prostate Forum at the 2016 AUA, Dr. Mark Emberton discussed the optimal timing for use of MRI. He began with a case of a man with two prior biopsies who was told that he’s “all clear.” An MRI was obtained before his 3rd biopsy, and a large midline lesion was discovered; prior biopsies had missed to the left and right of the lesion.
In the only trial randomizing men to TRUS biopsy or up-front MRI, detection rate was almost twice as high in the MRI arm (72% vs 38%). Of those who were TRUS negative and MR negative, the residual cancer rate was 30%. However, if TRUS was negative and MR was positive, there was almost a 90% chance of finding cancer. Thus it appears that MRI is driving the model. Importantly, it appears that men with low-grade disease were “systematically overlooked.” None of the 130 men with negative MRI had any Gleason 4 on saturation biopsy.
Dr. Emberton encouraged the use of MRI to aid in counseling, as PSA and DRE don’t provide much in terms of prognostic certainty. Meanwhile with MRI, we can provide a “probability map” of finding cancer, and suddenly the conversation is enriched. In a decision tree analysis, patients who had MRI performed up front had a decrease in the number of biopsies performed along with diminished false negative and false positive rates; they also demonstrated an enhancement in true positives and true negatives. Importantly, the three cost effectiveness studies that have been performed in this space all favor incorporation of MRI into the management algorithm. Uncertainties that remain include the need to biopsy in the setting of negative MRI, and the continued need for random biopsies to companion targeted cores. The PROMIS and PRECISION RCTs aim to provide answers to these questions.
Dr. Emberton concluded that MRI is the modern response to a man at risk for prostate cancer. Precise risk stratification is a requirement for a personalized approach to care, and this includes the utilization of MR-driven targeted biopsy.
Presented By: Mark Emberton , MD