Bone tumors can be palliatively treated using radiofrequency (RF) ablation with cementoplasty, radiation therapy, or a combination of the two. Treatment options differ in speed of response, extent of pain relief, and risk of subsequent fracture. Interventional radiologists Dr. Jason Levy and Dr. Sandeep (Sonny) Bagla discuss the results of their OPuS One trial study, the importance of cementoplasty after RF ablation, and how RF ablation with cementoplasty compares with other therapies.
We’ve provided the highlight reel below, but you can listen to the full podcast here.
The BackTable Brief
The preliminary results of the OPuS One trial, run by Dr. Levy and Dr. Bagla, have shown that some patients were getting pain relief within 24 hours after a single RF ablation procedure with cementoplasty using Medtronic’s OsteoCool™ RF Ablation system. According to Dr. Levy, the majority of patients saw significant pain reductions as early as three days post-ablation. Throughout follow-up, patients reported sustained pain relief up to six months post-procedure.
RF ablation with cementoplasty provides faster pain relief than radiation therapy with lower radiation exposure. Cement provides mechanical stabilization after RF ablation, and without stabilization, subsequent fractures may occur. Dr. Levy notes that most patients metastasize in the axial weight bearing skeleton, so filling with cement plays a critical role because of mechanics and loading forces.
Treating bone metastases with radiation alone often requires multiple touchpoints, and it can take three to eight weeks for pain relief. Dr. Bagla states that the biggest risk with radiation is fracture. He notes that 40% of patients receiving conventional radiotherapy do not experience significant improvement in pain. However, RF ablation with cementoplasty in combination with external beam radiotherapy has been shown to increase response rates from roughly 60% to 90%.
Image Courtesy of Sabeen Dhand MD
Disclaimer: The opinions expressed by participants of the BackTable Podcast belong solely to the participants, and do not necessarily reflect the views of BackTable.
OsteoCool RF Ablation Study Results
Dr. Levy and Dr. Bagla discuss the results of the OPuS One trial, which assesses clinical outcomes of patients undergoing a single RF ablation procedure using Medtronic’s OsteoCool™ RF Ablation system. According to Dr. Levy, some patients were getting pain relief within 24 hours. The majority of patients experienced significant pain reductions as early as three days post-ablation. Patients also reported sustained pain relief up to six months after ablation.
[So far, our OPuS One trial] results have been extremely encouraging. Patients were actually seeing significant pain reductions at three days, one week, one month, and three months. There was sustained pain relief up to six months after ablation and many times, augmentation, post-ablation.
What we have found is that this data is robust, not just in the size and the quantity of [the 100 patients we are reporting on], but the length of time we followed them up, which was out to six months. Obviously, you're going to have a high attrition rate with patients who have metastatic disease, so a large number of patients will unfortunately move on. But that being said, the rapid improvement in pain, I think that's what we were really focused on is, how quickly can you get these patients to improve? Downsides of radiation include length of time it takes for a patient to get better after treatment and the number of visits that a patient has to make in certain situations for say, standard EBRT. [RF ablation] has allowed patients to get a very rapid improvement. In the current environment, this becomes even more important, where patients can get in and out and get one treatment and get palliative.
The vast majority of patients are seeing pain relief already by three days and many of them, similar to a traditional kyphoplasty, may see pain relief pretty immediately. So, typically when I see a patient for other types of ablative therapy, I usually tell them that their pain's probably going to get worse before it gets better, and that may happen with this. But, we did see a decent number of patients who were already getting pain relief within 24 hours.
Why Cementoplasty is Important After RF Ablation
Dr. Levy states that the main advantages of RF ablation with cementoplasty over radiation therapy alone are the rapidity of pain relief and comparatively lower radiation exposure. Cementoplasty also provides mechanical stabilization after RF ablation, without which fractures are more likely to occur. For this reason, Drs. Levy and Bagla almost always perform cementoplasty after spinal lesion ablation. According to Dr. Levy, ablation provides a cavitary effect which allows for an even cement fill with less leakage into critical areas.
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.
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.
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.
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.
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.
Are there any circumstances after ablating a spinal lesion when you don't use cementoplasty?
That's a tough one, Mike.
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.
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.
RF Ablation with Cementoplasty in Comparison to Radiation and Combination Therapy
As a standalone treatment, RF ablation with cementoplasty offers more rapid pain relief than radiation therapy. Patients undergoing a single RF ablation procedure with cementoplasty have reported significant pain reduction as soon as three days post-op. XRT, on the other hand, often requires multiple touchpoints, and can take three to eight weeks for pain relief. Dr. Bagla states that the biggest risk with radiation therapy is fracture, and notes that 40% of patients receiving conventional radiotherapy do not experience significant pain relief. However, RF ablation and radiation are not mutually exclusive therapies. They can be combined. According to Dr. Bagla, RF ablation with cementoplasty in conjunction with external beam radiotherapy has been shown to increase response rates from roughly 60% to 90%.
[Radiofrequency ablation] is one of several options for pain palliation for patients with metastatic disease in the spine. Could you give me a better idea of where radiofrequency ablation should fit in amongst the other therapies, particularly radiation therapy?
What's nice about this procedure is that it can be performed under moderate sedation. The patients don't need to be intubated. We don’t need to worry about aerosolizing things like coronavirus. That takes a lower risk profile across the board, not just with viral spread, but of course, just with overall anesthesia-related risk. From a practical approach, this type of procedure really has been very popular. It is invasive, of course, when you compare it to external beam radiation. But, there are some drawbacks with radiation that we can cover as well.
As interventional radiologists, we're probably seeing less than 5% of these patients nationwide, while the radiation oncologists are seeing the vast majority of these patients. But, there's a couple of advantages radiofrequency ablation therapy holds over radiation. The bottom line is as a standalone treatment, the speed of effectiveness is going to be clearly better with radiofrequency ablation than with radiation. Radiation many times requires multiple touchpoints, if it's a multi-fraction, which almost always has become more of a standard of care. It can take three to eight weeks for pain relief. [Based on our OPuS One study results], we have seen patients with significant pain relief after three days. Again, at the end of the day, [radiofrequency ablation and radiation] are not mutually exclusive. They can even be combined together.
Jason gave a great summary of radiation and what the drawbacks are. Fracture is the biggest risk, and the other is that 40% of patients who get radiation don't even get better, at least with conventional radiotherapy. And Jason did mention combination therapy, and what's nice about combination therapy is there is data that suggests that when you offer RFA in conjunction with external beam radiotherapy, the response rates actually go up dramatically from roughly, say 60% to 90% and then you get an improvement in the rapidity at which you get pain relief. So, the combination therapy is very nice. There is the reality that Jason mentioned, where IRs are seeing less than 5% of these patients in their practice, say nationally. But, you can work closely with radiation oncology to offer that collaborative approach of simultaneously treating a patient. You might be able to offer a single fraction of radiation and then a single ablative and cement-related treatment, which is probably giving the best chance for immediate and long-term success. Would you agree with that, Jason?
I completely agree with that. In fact, it also serves a little bit as a practice building methodology, if you're willing to have more of a consolidative approach using RFA with cementoplasty, like what we're talking about, followed by radiation. Obviously, we're going to reduce their complications by eliminating their fractures and the patients are going to be better served with probably higher pain relief scores and better long-term, lasting effects.
Totally. It's a great tool for practice building, because you're not really competing with them, and by doing combination therapy with a cementoplasty, you're decreasing their likelihood of getting a fracture afterwards.
Dr. Jason Levy is a practicing interventional radiologist at Northside Hospital in Atlanta, Georgia.
Dr. Sandeep Bagla is a practicing interventional radiologist with the Vascular Institute of Virginia.
Host Dr. Michael Barraza is a practicing interventional radiologist with Radiology Associates of Baton Rouge.
Cite this podcast:
BackTable, LLC (Producer). (2020, June 16. Ep. 68 – RF Ablation Therapy for Bone Metastases [Audio podcast]. Retrieved from http://www.backtable.com/podcasts
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