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The Role of NanoKnife Focal Ablation for Prostate Cancer
Ishaan Sangwan • Mar 7, 2022 • 40 hits
The NanoKnife is a new therapy option for individuals with intermediate grade prostate cancer who would like to avoid the potential complications of a radical prostatectomy. Dr. Amit Patel and Dr. Ranko Miocinovic, early adopters of the NanoKnife System, discuss focal ablation technology on the BackTable Urology Podcast and share their perspectives on the NanoKnife system, the ideal patient for this new treatment, and how it compares to other prostate cancer therapies. We’ve provided the highlight reel in this article, and you can listen to the full podcast below.
The BackTable Urology Brief
• The NanoKnife System creates a focal ablation zone with precise margins which can be used to destroy tumor cells while minimizing nerve and connective tissue destruction.
• The NanoKnife System is ideal for individuals with intermediate grade 3 + 4 prostate cancer in one lobe.
• The NanoKnife System is also an option for older individuals with 4 + 3 disease who have contraindications to other therapies.
• Current evidence suggests that compared to cryosurgery, the NanoKnife System has a lower risk for swelling, erectile dysfunction, stricture formation, and urinary retention.
Table of Contents
(1) What is the NanoKnife System?
(2) Ideal Candidate for Nanoknife Focal Ablation for Prostate Cancer
(3) The NanoKnife System vs Cryosurgery for Focal Ablation of Prostate Cancer
What is the NanoKnife System?
The NanoKnife System consists of multiple electrodes that can be used to create a focal ablation zone with precise margins. It uses irreversible electroporation, or IRE, which generates an electric current that breaks up cell membranes and destroys cells. It is considered relatively safe, since it uses non-thermal energy, and minimizes destruction of nerves and connective tissue. The NanoKnife System has already had some success in safely treating other cancers overlying important structures, such as pancreatic cancers that wrap around the aorta or vena cava.
[Dr. Ranko Miocinovic]
NanoKnife is also known as irreversible electroporation, or IRE. And that's essentially using an electric current, to simplify, to break up the membranes of cells, and destroy them in such manner. The interesting thing about this technology is that it preserves the connective tissues and it minimizes destruction of the nerves.
So for example, you know, not to pull away from prostate cancer, but many centers and surgical oncologists are using it in treatment of pancreatic cancer in those tumors that are wrapped around the aorta or inferior vena cava, around very important structures. And they're able to literally ablate on top of these vessels, very safely and cause no damage because it doesn't destroy the connective tissue and the skeleton with these structures.
And so that idea is also hopefully going to translate into what we're doing here. And there's multiple studies to show that, the safety of that. but it is a non-thermal energy, basically.
[Dr. Amit Patel]
So I'll just add in, into that, that comment, for NanoKnife, the electricity is going through, the currents are going through two probes at a time. So these are needle probes that are, 17 gauge needles and they're going, strategically placing them, in the prostate, through a transperineal approach, you know, using a brachy grid and ultrasound guidance.
And the geometry of the probes and the number of probes that we use helps to dictate how the ablation zone is going to play out. So, if you use two probes, your ablation zone is almost like a cylindrical pill with, you know, rounded ends. If you use three probes, it's more of a triangular shaped zone. And if you use four probes, depending on how you're placing it, you're getting a more rounded cube like ablation zone, and 3D. So depending on your lesion size and how the lesion is within the prostate, you can adjust how many probes you're going to use to get an adequate ablation zone.
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Ideal Candidate for Nanoknife Focal Ablation for Prostate Cancer
The ideal candidate for NanoKnife focal ablation has an intermediate grade prostate cancer, ideally with a Gleason score of 3 + 4. There are also demographic considerations, since data from Europe and Australia has shown recurrence in up to 30% of patients. Dr. Miocinovic feels comfortable offering NanoKnife to any patient with a 3 + 4 disease, but prefers to only offer it to older patients with 4 + 3 disease. This is because these patients often have other comorbidities, and may not be good candidates for other surgical interventions. He also states that he prefers to offer the procedure to patients with disease in only one lobe. More long term data for NanoKnife may further shape these guidelines in the future.
[Dr. Ranko Miocinovic]
Yeah, that's a good question. So I think that clearly some of the data that was presented by the groups in Europe and Australia. there were certain series that showed recurrence in up to 30% of patients. And, you have to be, I think careful who you offer it to, obviously we're not going to be offering this to patients who have Gleason eight or higher because of the risk of metastatic disease and et cetera.
I think that Dr. Patel and myself have sort of agreed to offer it to any man, age wise who may have minimal, 3 + 4 disease. And I think for those men who have 4 + 3 disease, we would offer it in the setting of an older patient population, uh, maybe who are, who have other comorbidities, and who are not great candidates for surgery and who may not want to undergo radiation either. So I think 4 + 3 is perfectly fine. I just am not comfortable yet at this time offering to my 50 year old guy, for example. And this is why I think it's going to be important that we have long-term follow-up on this. I think we have short and intermediate term follow ups with these studies, but something on a longer term basis may convince me otherwise.
But for now, three-plus for anyone. And 4 + 3 for the older guys with other co-morbidities and Dr. Patel, you can, you know, answer this as well, but this is sort of our stand for now.
[Dr. Jose Silva]
And 3 + 4, only one lobe, two lobes?
[Dr. Ranko Miocinovic]
Yeah. I think that, uh, we want this disease to be on one side of the prostate. So essentially, you know, we feel that we can get hemi-ablation done if we had to, once you have disease, you know, both sides of the prostate. I don't think we would offer this at this time. So we are interested in offering to those men who have a disease, mostly left or right side of the prostate.
The NanoKnife System vs Cryosurgery for Focal Ablation of Prostate Cancer
The NanoKnife System can be compared to cryosurgery, another common option for focal ablation. According to AngioDynamics, the NanoKnife avoids damaging connective tissue, collagen, nerves, and blood vessels, leading to lower scar formation and lower rates of erectile dysfunction. Current data also suggests that the NanoKnife lowers the risk for urethral strictures, since it does not use a urethral warming catheter. There is also evidence to support that the NanoKnife System has a lower risk for swelling and urinary retention, and a lower perioperative time, making it an option worth considering for certain patients.
[Dr. Amit Patel]
One of the pros that we're seeing with NanoKnife and with other athermal approaches that may emerge, is that you're not damaging the connective tissue, the collagen structure, the nerves, and the blood vessels, that are around surrounding the prostate as well as within the prostate.
So your scar tissue formation, your side effects of erectile dysfunction are going to be a lot lower. In addition, you're not, significantly causing damage to the urethra as well. One of the, concerns about cryoablation is we have to use a urethral warming catheter, and we do have to maintain a certain distance away from the urethra to not cause sloughing, or even, strictures within the prostate or within the membranous urethra. In our early experience with NanoKnife, we have not seen that. We can be close to the urethra. You'll have a zone of urethra that's even treated with the current, but it's not causing damage to those, to that endothelial tissue. And so there may be some swelling but not damage. And I think that's a really important aspect when you're thinking about ablative therapies. And certainly the pros of NanoKnife is that you're not going to have significant, uh, scarring and scar tissue that's developing in these patients.
So our, our early experience, uh, you know, one of the biggest benefits is that with cryosurgery, I don't know if you recall at one point, urologists replacing suprapubic tubes, uh, at the time of cryosurgery because of the risk of retention afterwards. In my practice, I leave a catheter, a urethral catheter for seven days for cryo, for NanoKnife, uh, we're leaving catheters for three days.
So I think there's significantly less swelling, less risk of urinary retention after the procedure, the perioperative time, the time operative time is actually lower for NanoKnife then cryoablation. Typically for any cryoablation, whether it's whole gland or partial or focal ablation, it takes about an hour and a half 90 minutes of time. Sometimes up to two hours. With NanoKnife, we're seeing much faster operative times, anywhere from 45 minutes to an hour. So treatment time is a lot quicker. We’ve been doing our NanoKnife cases in a freestanding outpatient surgery center so these cases are outpatient. The patients do require paralysis for NanoKnife, they don't require that necessarily for cryoablation. But I think the biggest benefit is that less swelling in the prostate, lower risk of retention after the procedure.
Dr. Amit Patel
Dr. Amit Patel is the chairman of the urology department at Duly Health and Care in Chicago.
Dr. Ranko Miocinovic
Dr. Ranko Miocinovic is a practicing urologist with Duly Health and Care's integrated oncology program in Chicago.
Cite This Podcast
BackTable, LLC (Producer). (2022, February 9). Ep. 30 – Minimally Invasive Focal Therapy for Prostate Cancer [Audio podcast]. Retrieved from https://www.backtable.com
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