Bone metastases can cause significant pain in cancer patients. Unstable lesions can ultimately lead to fracture and other debilitating skeletal events. Interventional radiologists Dr. Jason Levy and Dr. Sandeep Bagla discuss radiofrequency (RF) ablation for the palliative treatment of painful spinal lesions, highlighting patient selection, goals of therapy, and follow-up care.
We’ve provided the highlight reel below, but you can listen to the full podcast here.
The BackTable Brief
Goals of RF ablation of spinal metastases include pain palliation and prevention of delayed skeletal events such as pathologic fracture and nerve/cord impingement or injury. These events occur most frequently with posterior vertebral body lesions. Drs. Levy and Bagla emphasize that ablation is safer and more effective for metastases within the vertebral body rather than paraspinal or extraspinal lesions.
Patients referred for palliative ablation often have widespread metastatic disease, frequently with multiple spinal lesions. Dr. Levy will treat multiple lesions if pain can be confidently localized to specific vertebral levels. Otherwise, patients with diffuse pain are often referred for radiation therapy. Dr. Bagla agrees with this approach, and adds that significant spinal instability should also be considered a contraindication to percutaneous ablation.
Dr. Levy and Dr. Bagla typically see patients back in clinic at two weeks following spinal RF ablation. Additional patient touchpoints during follow-up include routine imaging ordered by the oncologist as well as new imaging for recurrent or new pain. If there is no pain improvement at two weeks, it is possible that the lesion may have been undertreated or that an adjacent lesion is responsible for the pain, according to Dr. Bagla.
Image Courtesy of Jason Levy 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.
Patient Selection, Lesion Selection, and Goals of RF Ablation Therapy
Candidates for RF ablation therapy include patients with metastatic disease and pain localized to osseous metastases. Although there are no spinal lesion size criteria, Dr. Levy states neurologic deficit from a lesion is an excluding factor. Significant spine instability requiring surgical fixation is another, according to Dr. Bagla. Diffuse pain is difficult to target with RF ablation. However, multiple lesions can be treated as long as pain can be isolated. Dr. Bagla states that the primary goal of RF ablation therapy is to palliate patients and provide enough pain relief for individuals to stay on systemic therapy. Secondary goals include preventing a delayed skeletal event such as fracture, severe compression, or retropulsion. Because delayed skeletal events almost always occur in the posterior vertebral body, both Dr. Levy and Dr. Bagla emphasize effective ablation posteriorly.
What are the primary indications and the goals of radiofrequency ablation therapy for spinal lesions?
The primary goal is to get patients out of pain. So, to palliate these patients, they obviously have advanced disease by nature of the fact that they have bone metastases. Our primary goal is get them out of pain so that they can go on and live a good quality of life and stay on their systemic therapy, which many patients cannot tolerate because they're in so much back or pelvic pain that they don't want to tolerate their systemic therapy. The secondary goals are more about preventing a delayed skeletal event, preventing that severe compression or retropulsion. We don't follow patients with serial imaging who come in with your typical osteoporotic compression fracture, but if you do follow your oncologic patients, you will note that those patients who have lesions in the spine, when left untreated, end up going on to fracture. They end up coming back with epidural extension in time. And those are the types of events we're trying to prevent as a secondary effect of the procedure.
What are you looking for in terms of size and location of lesions in identifying appropriate targets for ablation?
So, there's really no size criteria. The most common thing that serves as an exclusion is a neurologic compromise, so somebody who has neurologic symptomatology. I will treat occasional patients with multiple lesions, but I'm not going to treat somebody if they can't come into my clinic and say, "I hurt here and here." I need them to be able to localize where the pain is. Now, it's not always perfect, a lot of these patients will get wrap-around pain and our ER colleagues may have worked them up with a CT pulmonary angiogram to start with and sure enough it's actually a T5 met. But, the bottom line is I want the imaging to match the location of pain. If they just have diffuse pain, it's very hard to improve upon that and we usually refer those to our radiation colleagues.
Yeah. I would agree. In those patients who I'd say are not candidates, we tend to shy away from patients who have diffuse disease all up and down the spine and don’t really have a focal spot that you can say, "This is where the pain is." Those patients might be better for a wider net of EBRT and/or biologic or bone stabilizing agents. Obviously, there are some patients who we turn down just because they're surgical candidates. Some of these patients have such instability that they do need fixation, and so that does happen where you get patients who are so advanced. These cases are important to consult with your spine surgeon and make sure that they have spinal stability. But, I absolutely agree with Jason's methodology, and I think taking that approach really keeps your patient flow consistent. The oncologist in the area, the radiation oncologist, the spine surgeon—they all know the kinds of patients you're going to put on the table and what your goals are for your therapy.
How do you approach lesions with significant extra spinal extension?
We both tend to say, "Don't chase those extra spinal lesions with bone ablation." If you go and turn on a probe, whether it's radiofrequency or any other technology, and you turn that on say in the psoas musculature or somewhere else, you're going to end up having a problem. Patients are going to get resultant pain from burning or freezing that tissue. If you get very aggressive with lesions, that can add to the neural foramina. While you could be a little bit more aggressive there, you definitely run the risk of getting an exiting nerve root injury. You can use thermocouples, and there are protective techniques that you can utilize, but I always make the comment that if you just treat the vast majority of patients who aren't those, you're going to have great results. You're going to make a real big difference in these patients' lives.
Yeah. I agree completely. Everything comes back to what our goals were, and it's pain relief and preventing delayed skeletal events. So, delayed skeletal events, when they occur, they almost always occur in the vertebral body, at least posteriorly. So, really making sure that your ablation is effective posteriorly, in my mind, comes first and foremost. Chasing tumors that are in the paraspinal soft tissues, I find to be both ineffective and overzealous. And, really, the bottom line is there's data to support not chasing that. If you look at some of the older studies, we know that the larger tumor ablations did not result in better pain relief, but in fact, it was just ablation at the bone-tumor interface.
You talk again about delayed skeletal events. Is there a role of using this for preventing that, beyond just pain palliation? I mean, is there a role for prophylactic ablation on lesions at high risk of fracture?
Mike, it's a great question, and it is one that's probably not yet, to my knowledge, well-answered because it's very difficult to stratify those patients. There are grading scales for which certain factors increase the likelihood of instability of a lesion. For example, if that lesion were at a hinge point or if a certain percentage of the bone was replaced. But, because there's not necessarily a set guidance on it, a lot of it is left open to individual interpretation.
Yeah. I agree with you. I mean, there's my opinion and then there's the reality. My opinion is similar to a surgeon who would be looking at something that's got an impending fracture. He'd be going and treating it. I do think that certainly for certain metastases, some of these renal cells, thyroid mets, or other real vascular and/or lytic lesions that really have a high propensity to go into fracture, I personally believe in an approach that is very aggressive upfront. Then you step back and you look at the reality and what almost every payor will accept for an indication. That's not one of them. So, you're put into a little bit of a challenging location if you believe that it is worthwhile, which I do. I agree with Sonny that we don't really have good data for that. Not sure we'll ever get that either.
RF Ablation Therapy Follow-Up Care
Most patients with successful RF ablation will start experiencing pain improvement within the first 2 weeks following the procedure. Dr. Levy and Dr. Bagla usually see patients back for the first post-op visit at two weeks with additional patient touchpoints when new imaging is ordered by the oncologist. If there is no pain improvement at two weeks, it is possible a spinal lesion may have been undertreated. Alternatively, there could be an adjacent lesion causing pain, according to Dr. Bagla.
How and when do you monitor the outcomes of the procedure? When do you start seeing these patients back in clinic?
We tend to see them back two weeks after the procedure. Similar to other ablative technologies, you may get any increase in pain just related to edema in the first 24 hours, for which we sometimes give patients an additional pain medication or a steroid. Invariably, their pain will significantly improve by the time you see them back at a week or two weeks. So, just for convenience, we see them back at that point. Then, following that, we tend to not see them back. We do manage their imaging and whatnot that needs to be done through their medical oncologist.
Our touch points are almost identical to yours. The clinic calls the patient the next day and if they're still having pain daily, until that starts to improve, we see them at two weeks. And then, just like you, we don't order follow-up imaging unless we're worried about something or the patient has a new or recurrent pain. We tag along with the oncologist's imaging, but we do request the patients to let our office know when they're getting imaging. That becomes an additional touch point, even if it's just an imaging touchpoint, where we can see the patient's follow-up imaging.
Two reasons why this is important. One, from the imaging standpoint, patients are limited by their ability to financially pay their copays associated with imaging. Two, we want to make sure that we're not stepping on the toes of medical oncologists who may have imaging that they're timing, related to their systemic therapy. From the clinical follow-up standpoint, invariably if they're not better at two weeks, there may be something going on and you're not realizing it. It is a possibility, albeit rare, that you undertreated the lesion. But, they do have metastatic disease, so they could have an adjacent lesion that's causing the pain. They may need an epidural injection or an exiting nerve root block injection. We don't want to take ourselves out of the whole treatment team and just say, "I did this procedure and I can't really assess why else they have pain." That will happen, and if it does, I think it's important to see them back and make sure you can offer them some other treatment that they may need for palliation.
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 Alliance in Nashville.
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
The Materials available on the BackTable Blog are for informational and educational purposes only and are not a substitute for the professional judgment of a healthcare professional in diagnosing and treating patients. The opinions expressed by participants of the BackTable Podcast belong solely to the participants, and do not necessarily reflect the views of BackTable.
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