Irreversible Electroporation at Sylvester Comprehensive Cancer Center: An Interview With Govindarajan Narayanan, MD

IO360 sat down with clinical editor Govindarajan Narayanan, MD, of the University of Miami Miller School of Medicine Sylvester Comprehensive Cancer Center (SCCC) to discuss the use of irreversible electroporation (IRE) at SCCC.

Q: Please explain the technique and technologies used during IRE.

A: Irreversible electroporation or IRE is a technology that has been now commercially available over the last 4 years from AngioDynamics with the name Nanoknife. It is a predominately nonthermal ablative technique that uses high-voltage, low-energy D/C current to cause cell death. The electrical energy creates multiple pores in a cell membrane and disrupts the homeostasis mechanism across the cell organelles and that’s the way it induces cell death. Since it’s mostly nonthermal, you are able to get away from the heat-sink effect, which you would have with thermal ablative techniques. This technology has an FDA 510k approval for surgical ablations in soft tissues and currently using this technology in organs is considered off-label.

Q: When did you begin using IRE in your facility?

A: Well we started using IRE in our practice January of 2010 and over the last four years we’ve performed over 300 treatments and we’ve used the technology mostly in areas where we cannot use thermal ablative techniques so it’s given us the ability to create ablations which are close to vessels and ducts and other critical structures. The key is that even though we’ve done a pretty large series this is still the early stage of use of the technology and there’s a lot more to be learned but overall what we’ve seen is it’s safe and we’ve been getting some good results with it.

Q: What data have you collected on IRE?

A: We have published a few papers on our experience with IRE. We started with comparing the pain post-procedure between radiofrequency ablation and IRE and the most significant study that we’ve published so far is on IRE in pancreatic carcinoma in patients who are either in a stage 3 or stage 4 of pancreatic cancer and who are being treated with chemotherapy and radiation, now running out of options. So the first-experience publication was on 14 patients and what we found was that it could be done percutaneously. Until now, the largest series available was performed by surgeons in an open manner, so we showed that it could be done percutaneously and safely and we got reasonably good results in the patients.

We will be presenting our experience with the first 30 patients at the SIR meeting this year in San Diego where we are going to present an abstract. Today, we’ve treated about 46 patients. Again, we continue to learn, but our interim analysis of the patients has shown that the mean overall survival of the first 30 patients was about 11 months and that was from the date of the IRE, which is encouraging and something that needs to be further studied.

Q: What are some tips and tricks that you learned since you began using IRE?

A: The main thing that we’ve learned over the last 4 years is that IRE does not replace other ablative tools that we have. It’s not a silver bullet. What it has done is given us the capability of performing percutaneous ablations in organs and areas where we typically would not be able to go with what is currently available in the market as far as using thermal ablative techniques or cryoablation. It has treated lesions close to the aorta, patients with metastatic nodes, and lesions close to the gallbladder, colon, and stomach.

The other key thing that we’ve learned is that planning is crucial with this technology. Unlike other ablative tools, this requires placement of multiple needles and placement between the needles is critical and therefore you need to spend sometime to plan the treatment. And there is a learning curve attached to this technology. Most interventional oncologists are used to using a single needle in radiofrequency ablations and microwave ablations where you commonly place the probe in the center of the ablation to create the treatment and then if you have additional areas to be treated, you pull the probe back. Cryoablations is a technology where you use multiple needles to build a compound lesion but again the spacing in this technology is critical, you want to stay under 2.2 cm between the needles.

We also learned that it’s important to have a discussion with you anesthesiologist because they play a very vital role in this procedure. Unlike other ablative procedures, which technically can be done with conscious sedation, you require general anesthesia for IRE and it has to be done with complete muscle relaxation so your anesthesiologist plays a very key role in the procedure so having them nearby and having them understand the procedure and technology is also very important.

Needle placement is something that interventional radiologists do routinely, so once you perform 5 or 6 procedures you get the feel of how to do it, planning the access, the trajectory to get the needle to the right place safely—that’s very important.

Another key point that I keep mentioning whenever I talk about the technology, even though the technology is safe near vessels, you’re still placing a very sharp needle so the access has to be safe because you could still cause physical damage to a blood vessel with the act of placing the needle. Also, it’s important to understand the clinical stages of the patient and when to use this technology. I say this to stress the importance of a metastatic work-up of these patients. Often we see them in clinic and we’re focused on the area we’re going to treat and we might miss what’s going on in the rest of the body. If a patient has extensive metastatic disease elsewhere, this might not be the best option. Doing a thorough work-up on these patients is important. We have also learned not to use IRE just because we can do it. It must be a clear benefit to the patient, taking into consideration the pros and cons.

Q: Could you describe the use of IRE in your facility as it fits with other treatments?

A: Our practice uses all the ablative tools that are available now: radiofrequency ablation, microwave ablation, cryoablation, IRE. We perform more thermal ablations than IRE. What we’ve learned over the years is to place IRE in the treatment algorithm. What we do in our practice is that if we have lesions, which are amenable to thermal ablation away from critical structures, we use those. Radiofrequency ablation has been around for several years. There’s a huge amount of literature and experience with that and we’re very comfortable using that. When we come across lesions that are close to critical structures, mainly vasculature, the gallbladder, or the bowel, then we tend to lean toward using IRE in those cases. Again, with the caveat that everything is weighed on a case-by-case basis, it’s presented to a multidisciplinary tumor board and if they feel that this would be an ideal candidate, then we use it. We also use it exclusively in the pancreas whether we have a patient referral to us that is the technology that we use, we have not used any other technology in the pancreas. So, these are the two areas where we feel it has a niche application in our practice.

Q: Do you have any advice for IO clinicians who want to beign using IRE?

A: If you are just getting started in interventional oncology, this would probably not be the first ablative tool that I would suggest you add to your practice. But if you have a practice that’s already performing ablations, this would be a good additional tool to expand the scope of what you do and what you can accomplish with your patients so you can offer more to your clinicians and your patients. But again, my suggestion would be to not begin with IRE because there’s a learning curve and there are coding, reimbursement, admission, and anesthesia issues that need to be worked out, so it’s a programs to bring in IRE to your practice.

Suggested citation: Ford J. Irreversible electroporation at Sylvester Comprehensive Cancer Center: an interview with Govindarajan Narayanan, MD. Intervent Oncol 360. 2014;(2)2:E8-E10.