The MOTION Study: Evaluating Cryoablation for Painful Bone Metastases

[Dr. Jack Jennings]
Why cryo? We do a lot of it in bone for many reasons. One, you can see the ice ball. Now, when I say that, when it's dense bone, you don't see within the bone, but you can see it extending beyond the bone. Two, it's a modality that we can sculpt. We can make geometries that you can't make necessarily with some of the heat-based thermal ablations. Typically, it's less painful.

Matt's group published that trial, RF versus cryo as far as pain from the procedure. Finally, where we are, I think we're going to talk about this, when we are close to nerves and other structures, they are much more forgiving with ice than they are with some of our heat-based modalities. That's a 30,000 foot overview of why cryo in bone.

[Dr. Jacob Fleming]
Absolutely. Thank you for that explanation. The MOTION Study really is very impressive. As you said, there's really the all-star cast. I was looking and thinking this is the Avengers of musculoskeletal interventional oncology. It's just a really impressive cast of clinicians who participated in this from all around the world. One of the things that really struck me was just how many different bone metastasis sites there were. There obviously were some recurrent ones, but this is quite different from some of the other studies that have focused more so on spine ablation.

In this study, the most common index tumor location was actually in the rib in about 24% of patients and a smattering of all over. One thing I wanted to touch on is bone mets, of course, can show up anywhere. There are places where they are more common, and some of these have their own consternation associated with them. For example, ribs can really be difficult in some ways. One thing I was curious about, not necessarily limited just to the trial, but your experience ablating a lot of these lesions, tell us about some of these recurrent sites such as rib or ilium and maybe some of the particular challenges that come up with those.

[Dr. Jack Jennings]
Yes. One caveat, one thing I will tell you. Spine is the number one site of metastatic disease, which I think you were alluding to. Cryo is done less in the spine for many reasons. A, you've got the spinal cord and nerves, and I call it the silent killer, meaning even under conscious sedation, you can take out a nerve in the spinal cord versus heat, much more thermotoxic and patients under conscious sedation will not allow you. If you look at all these spine metastatic trials, treating those with thermal ablation, radiofrequency ablation is number one hands down. In fact, that's the first modality that got us even ablating anything with osteoid osteomas.

This trial, very few spine, and there's a reason for that because it's not a great trial. Those are very complicated, and that goes to answering your question about how complicated. Now, so, pelvis is the number two site of metastasis. Not surprising that if you take sacrum, pelvis, ischium, all those in there, that would, I don't remember all the numbers, but they for sure add up to be number one. Ribs are very common. These chest wall, pleural base, lung, whether it's primary lung or metastatic lung, those are very common metastases and ones that we ablate.

We're also taking out the intercostal nerve. I believe you've had Prologo on here, given there's nerve spiel, for sure, my good friend up on the pulpit. You're really doing a double good thing. You're treating the met as you're taking out that intercostal nerve, which helps with that chest wall pain. If I were to give the most challenging, it's anywhere near a nerve. I do use cryo pretty consistently in the posterior elements of the spine, or when there's paraspinal soft tissue.

With those, I use evoke potentials, and I think we talked about that, your passive and active thermoprotective techniques, and then posterior acetabulum, the sciatics right there. That's another cautionary place. Really, those are the ones that I find the most challenging. Anybody can put a needle in any of these places, it's staying out of trouble, and that's what I find the most challenging.

Yes, I'm not surprised. We endorsed doing real-world stuff, and this is real-world stuff. One point I would make, and you can correct me on this because I don't have it in front of me, but it was a huge number of, it was close to 60% were greater than four centimeters. Big lesions. I think it was greater than four centimeters or more. It was two-thirds of them. That's real life. That's less than ideal because we would love to catch these before, but this is all part of getting this message out to our oncology colleagues and whatever.

These were real lesions. These weren't like chip shot, one, two-centimeter ditzels. These were big boys. If you've got it in front of you, I think greater than four centimeters is close to 60-some percent, right?

[Dr. Jacob Fleming]
Yes. The mean size is actually 5.7. Pretty impressive and with a large standard deviation, they have about 60% or more than four centimeters. These are serious metastatic lesions. I think the fact that it was skewed so far in that direction, and the patients really did quite well with this. Could you just briefly summarize for us again the results of this and how patients did, how this helped out?