Palliative Effects and Risk Reduction Using Radiofrequency Ablation with Cementoplasty

[Sonny Bagla]
In the fracture patients, it's those who have a lytic lesion with an associated fracture, let's say, compression deformity, where the cement stabilization with ablation really is and should be a first line therapy. Then, radiation therapy can augment that for sure. The reality is, unless you stabilize them, they will probably go on to fracture adjacent levels, and they will not get significant pain relief by just radiation alone. And then, you look at the patients who don't have compression deformities, but still have a lytic, intrinsic fracture in the bone. Those patients in the setting of say, oligometastatic disease, four or less lesions, those patients would be good candidates for RFA and cement. And really in those patient populations, we're trying to avoid a delayed skeletal event, something like a subsequent fracture or retropulsion or tumor extension posteriorly into the canal.

[Jason Levy]
Equally important to the therapy is not just the radiofrequency ablation, which has a major role, but the ability to cement afterwards and mechanically stabilize the bone. This is unlike radiation, which has a real risk of inducing fractures. And that is depending on the type of radiation, whether it's multi-fraction radiation or external beam, which probably has the lowest risk, but still has a risk. Single fraction, external beam has a more substantial risk. Then, with SBRT, there are reports showing it leads to 11 to 39% of subsequent fractures. … [With RF ablation and cementoplasty], we have the ability to mechanically stabilize and we really don't eliminate future therapies. So, I think advantages are speed of relief and obviously that there's no radiation.

[Michael Barraza]
Wow.

[Jason Levy]
Most of these patients metastasize in the axial weight bearing skeleton. So, that's where cement plays a huge role because of mechanical stabilization and axial loading bones. I'm typically using [RF ablation] in combination with cement... I’m looking at an axial weight loading bone, traditionally the sacrum, the T&L spine, the entire spine, but I use this quite a bit in the acetabulum also. I think this is a great therapy in the acetabulum, where you end up using large volumes of cement after you ablate. I don't personally use this in long bones. Although it's very effective with axial loading force, it is not effective with torsional force.

[Sonny Bagla]
I think when you're stabilizing the bone, especially in patients who have lytic lesions, within that bone obviously there is some degree of instability, especially if the lesion is at hinge points, like T12/L1 for example. Having the ability to stabilize that bone when you have tumor replacement in the vertebral body is important. I'd say, we are fair under-treaters of patients who have lytic metastases with intrinsic fractures within the bone. We're all looking for this massive compression deformity of the bone, but we don't have to wait until somebody loses 40% of height of their bone before we know that they're going to get an improvement from a treatment like this.

[Jason Levy]
Yeah. Just to add onto the rationale of under-treating, I think I, as an interventional radiologist, before I was doing a combination of RFA and kyphoplasty, certainly at least in the spine, I think I was probably turning away more patients than I should have. So, someone with a blown out posterior wall, I would be turning them away. But when I started adding radiofrequency ablation into the practice, it really actually provided me a higher level of comfort in treating these patients. The rationale is that the ablation actually provides you more of a cavitary effect in that area, so that you will have more of an even cement fill with less leak into a critical area.

[Michael Barraza]
Are there any circumstances after ablating a spinal lesion when you don't use cementoplasty?

[Jason Levy]
That's a tough one, Mike.

[Sonny Bagla]
Yeah, it's a tough one. Six, seven years ago, when I was doing ablation in the spine with RF early, indications that we used for cement were purely lytic lesions in older populations. If you're going to ablate a lesion that's almost entirely blastic or nearly almost entirely blastic, and it's in a young patient, one would argue, is there really a role for cement? I don't know. That being said, I think that you're already there, and there's no significant increased risk if you do it carefully after ablation. So, I tend now to invariably always cement after ablation.

[Jason Levy]
I always cement, and I do it because of the mechanical stabilization. There's different mechanisms of pain. There's the tumor pain coming from the cytokines, and then there's the mechanical pain, and even sclerotic metastases can have mechanical pain. The sclerotic cases I actually now have learned to worry more about cement migration in, much more so than the lytic cases, where I feel like I have a little more control. Sometimes in those sclerotic bones, it can come out a little more forcefully when you're putting it in, but in the acetabulum, sacrum and the weight bearing axial skeleton, I always use cement. I guess, with a few exceptions, maybe if I'm treating something down at S4, a very thin part of the sacrum, I might just ablate that.