Give us your thoughts about using MRI in three scenarios: for upfront screening, an active surveillance situation, and in patients with a previous negative biopsy with PSA still rising. Starting with primary screening, what are some of the challenges and benefits of its use in each of those areas?
Primary screening would involve a man with an elevated PSA, suggesting clinical risk of prostate cancer. Obtaining an MRI before the first biopsy to minimize the number of men who need a biopsy or target areas that might have higher risk cancers makes a lot of sense. But as of right now, the cart is before the horse.
The good news is there are trials in this space. One published study, PROMIS (PROstate MRI Imaging Study), suggests this strategy might be useful. Importantly, that trial was done in Europe where MRIs are significantly less expensive. In the U.S., a few sites are now participating in an international trial that recently completed accrual, and our center is fortunate enough to be one of them. It’s called the PRECISION trial (PRostate Evaluation for Clinically Important Disease: Sampling Using Image-guidance Or Not?), which is addressing the same question.
Importantly, I do not think it’s good-quality care right now for every man going for his first biopsy to have an MRI beforehand. The National Comprehensive Cancer Network (NCCN) guidelines specifically say it is not the standard of care but there’s emerging evidence that it might be useful at some point.
The obvious concerns with prostate biopsy are the infectious complications and resistant organisms, which appear to be increasing, and MRI alone could possibly eliminate that problem. If MRI was used as a screening tool and you still didn’t find cancer, would you still not do a random biopsy?
That’s where it’s very important to look at your own institution’s data, which I realize sounds “ivory tower-ish.” However, I can share an example from our institution. Historically, based on the published data, men at our center with a “negative MRI” always had a systematic biopsy out of fear of missing meaningful cancers that weren’t visualized on MRI. We then looked at our own data, which shows that if you have a negative MRI, there’s only a 5% chance a biopsy-detectable Gleason 7 cancer or higher was present. I share that information with men. Most men will say, if the risk is only 5%, they’re going to skip the biopsy. Other men still want to proceed.
The totality of the data in the urologic literature varies with respect to that percentage, but it ranges from as low as 1.83% risk of Gleason 7 or higher with a negative MRI in an Italian study to as high as about 16% in some earlier MRI studies.
Another big issue, as you well know, relates to the quality of the MR images and the expertise of the people reading them.
At our center, a lot of patients come in with outside MRIs, and we load them into our system. I uniformly show the images to our best prostate radiologist and ask him: Is this a quality MRI? If the answer is no, we repeat it. If the answer is yes, I have him read that MRI, and his reading sometimes agrees with the outside radiologist and often does not. We really rely on his expertise.