MRI-guided prostate interventions appear to have a bright future combining with the latest and greatest radiation therapy techniques to make prostatectomy and no therapy at all the least attractive options for most men with low-to-intermediate-grade prostate cancer. The evolution is largely being propelled by the side effects of the surgery when considered alongside the safety, efficacy and precision of the up-and-coming nonsurgical alternatives.
At the University of Texas Medical Branch and Island Medical Imaging in Galveston, interventionalist Eric Walser, MD, the institution’s chair of radiology, is one of just five or six U.S. physicians offering MR-guided focal laser ablation to these patients.
Walser lead-authored a clinical-perspective article in the October edition of the American Journal of Roentgenology reviewing the technique’s proven value and outlining its current state and future outlook. He took questions on the material from HealthImaging.
HealthImaging: What opportunities already exist for greater use of interventional MRI for prostate care, and what new avenues do you expect to open over the next five to 10 years?
Walser: There has been a push away from things like CT because of the radiation. You’re seeing a lot more MRI being done. Our MR scanners are pretty much full all the time, and the opportunities for the prostate are really amazing. The 3 Tesla was approved in 2004, and it was the first imaging modality that could actually see prostate cancer. That’s when this all started. Before that, the only way you could diagnose prostate cancer was doing random biopsies every year.
And so we are now rapidly moving away from that model to more of a breast imaging type of protocol, where every year a man gets an MRI of his prostate if his PSA is elevated. If you see a focal cancer, typically you go to biopsy. And then on the basis of that biopsy result, you decide what options you have. The traditional option is either watching it and doing nothing or going straight to radiation or surgery. And radiation and surgery have quite a few complications associated with them.
We found that focal ablation with a laser fits in nicely between doing nothing and doing radical surgery. So it’s become, in my mind, a method of choice for people with low to intermediate risk prostate cancer.
With the MRI guidance you can also precisely navigate to the lesion for targeted biopsy, correct?
That’s right. We take a needle, push a button and take a picture to confirm that the needle is in the tumor. It’s very accurate. We have over 95 percent sensitivity doing MR-guided biopsies, whereas the urologists doing them blindly just have about a 40 percent sensitivity. So you really can think about it like breast care. It’s very similar to that model.
The need for nonmagnetic interventional instruments must present a challenge.
Yes, it’s always more expensive. The other thing is that a CT scanner is shaped like a doughnut, where an MR scanner is more like a tunnel. It’s hard to work inside there. I can put my hands in there, but when I’m trying to place needles in there, it’s a lot more cumbersome.
I’m going to Boston in a few weeks to look at a robot that could assist in the MR environment. The one I’m looking at is for use with CT, but the potential is there to convert it into something that is MR-safe. It’s very neat technology.
Insurance is another major hurdle MR-guided prostate care needs to clear.
That’s probably the number one hurdle we face. Despite the fact that our procedure is cheaper and safer than surgery, the insurers refuse to pay for it. It costs between $20,000 and $30,000 to have this procedure done. In spite of that, we have done more than 200 patients [since the program started in 2013]. People will pay out of pocket for this procedure.
Another hurdle is that the interventional MRI usage is hampered by the fact that most practices fill up with diagnostic patients every day. That’s a big revenue generator for most practices. If you go into an interventional magnet and do two procedures, you’re taking away diagnostic time. That’s a big hindrance right now to wider adoption.
The third hurdle is urologists. They have to pay for their da Vinci robots and their radiation-producing machines. My referral pattern is self-referral. Urologists won’t send me anybody. They are not on board with this procedure because they can’t do it in their office and they feel like it hits their pocketbook.
The patients themselves are in a bind a lot of times. They want that cancer out of there, but they don’t want the side effects that are going to come with removing it.
Yes, and with ultrasound guidance you can’t guarantee them you’re going to preserve their sexual function. About 30 percent of the time, the patients do have troubles after the ultrasound-guided procedure. With MR, we have had less than 1 percent risk of erectile dysfunction and almost no urinary problems at all. In fact, urinary function tends to improve after laser ablation. We’ve had many guys call and tell us that they’re urinating like a teenager again.
We are currently taking scores at six months and one year that look at erectile function and their urinary function. Urinary function significantly improves, as a whole, while erectile function stays the same. That’s the next study we’re going to publish. It will be on about 100 patients with a one-year follow-up. And we are really focusing on safety, because the recurrence rate is such that prostate cancer is really hard to talk about unless you get five- or 10-year data. And we don’t have that yet.
It sounds like patient demand is going to gradually drive adoption of MR-guided prostate intervention even though the training curve is long for the interventionalists, as your AJR study mentioned.
I can tell you that, as more and more men find out about this, we get more and more business. Right I have four new patient cases to review that just came in this week. None of them are from Texas. Men are traveling here to get this.
If you get surgery, obviously you can’t get surgery again. You can only get radiation. If you get radiation therapy, you can’t get surgery, because it causes too much tissue scarring. So the good news about focused laser ablation is that it leaves all your options open. And that is kind of the essence of what we are going to publish next.