Urologic Oncology

SLIDES & TRANSCRIPTS
Saturday, December 6, 2003

Radiofrequency Ablation

McClellan M. Walther, M.D.

Slide 1:

Thank you. I'd like to just go over our experience here with radio frequency ablation. A lot of the fellows that have come through have taken an interest in this technology, and it had a lot to do with getting these protocols running, so I'd just like to thank them, in particular Brad Wood, who is our interventional radiologist, who has been a huge help in treating the patients.

Slide 2:

We became interested in this because we see patients with multiple renal tumors undergoing multiple operations, and we were looking for an alternative, less invasive way to treat these patients.

Slide 3:

Radio frequency ablation was published in Europe . There are multiple devices available. We went in for the RITA one, which was the first one available, although multiple other ones have become available since then. One of the primary motivators was the fact that it was fairly cheap to get started in this technology.

Slide 4:

The 50 watt RITA was the first one that was available in this country. That is the one we started treating patients with. There was a little bit of toxicity data from the European literature, but we weren't comfortable with that, so we started treating a few patients on protocol immediately before nucleation procedures, and then followed them looking for any unusual toxicity compared to the numbers of patients that we are used to operating on here without RFA.

Slide 5:

We treated five kidneys, 14 tumors, saw the expected things on ultrasound after treatment, which is loss of blood flow on color Doppler, the micro bubble formation. It is pleasing to see the tumors turn brown from the cautery effect. We did not do super vital staining on these guys, and just saw some more subtle defects.

Slide 6:

The thing we were most interested in was looking for any unusual changes in renal functions, which we did not see.

Slide 7:

That made us feel comfortable about going on and treating a larger group of patients, using this as the primary method of treatment. Because these people have hereditary forms of kidney cancer, we did not think they needed biopsies. We thought solid enhancing masses were renal tumors. We treated patients who had tumors with what we thought was adequate renal function, that were growing over a year, and we initially tried to treat all patients percutaneously with this 50 watt device.

Slide 8:

Our definition of a tumor was something that enhanced greater than 20 Hounsfield units after treatment. We had a gray zone between 10 and 20, and we thought we were well treated if there was less than 10 Hounsfield units uptake after treatment.

Slide 9:

We treated 32 tumors from the different patients we see here, and had a minimum of one year follow up.

Slide 10:

We saw shrinkage of the tumors. Unlike cryo, most of these tumors do not go away. There is a residual defect in most of the patients that you continue to measure. We saw a decrease in Hounsfield units, which I will go into a little bit more.

Slide 11:

These are typical things pretreatment, post treatment. The diameter that we are measuring is actually tumor plus normal kidney that has been killed by the treatment. So you end up measuring the whole thing, and it is hard to tell what is tumor and what is not. So the diameter is a little bit misleading, and we do depend on the contrast uptake to really measure what is going on.

Slide 12:

Based on the Hounsfield units with the 50 watt device, we had about a 62 percent success rate in following these patients, which was sort of disappointing. I think the manufacturers appreciated that this was an underpowered device, and all the manufacturers have gone to 150, 250 watt devices.

Slide 13:

In this group of patients, we saw some hematuria, some muscle and neural irritation, but no effect on renal function as measured by serum creatinine, creatinine clearance and differential renal scan, so we carefully looked at renal function.

Slide 14:

One patient is in a category by herself. This is a patient with VHL, who six months before we treated her had a six centimeter tumor. In our experience, VHL patients with six centimeter tumors, 25 percent of them develop metastases unrelated to RFA. These patients develop metastases 15 months after RFA in the lung as well as in the area of the treatment. So we don't know if it is related to tumor seeding or if it is related to the natural history of the VHL in this patient. This is the only patient we are seeing with any evidence of spread here.

Slide 15:

Based on the 50 watt device, we thought it was reasonable to try to treat all comers at this point. We had a more powerful device, 200 watt devices were available, so we try to treat everybody percutaneously when possible, and those that we couldn't do percutaneously we would do laparoscopically.

Slide 16:

Because we were going to try to treat all comers, we didn't feel comfortable with these umbrella devices, so we switched to the Radionics device, which is a single needle that you can more safely insert into the renal hilum and sinus of the kidney.

Slide 17:

The people we treated laparoscopically basically had a contiguous organ that could not be cooked. We would put in a 12 millimeter port for ultrasound, a two millimeter port for the RFA probe, because we didn't want to cook the skin if we could avoid it. We would monitor treatment with ultrasound visually and with whatever the output of the device was, either temperature or impedance output.

Slide 18:

These are reasons to do laparoscopy, either tumor next to bowel, pancreas or next to the ureter there. Those were our primary indications. When you blow the people up laparoscopically, it is amazing how everything falls away, and you have to do very little mobilization usually to get to the tumors.

Slide 19:

This is the only patient I am aware of that we presented to the radiologists and as a group decided not to treat. Pretty much in all the cuts there was renal pelvis, vessel, vessel, vessel right next to it, and we just weren't comfortable treating that one patient. But we have treated a number of other central tumors.

Slide 20:

In all, with one year minimum follow up we have treated 27 tumors with an equal split laparoscopic and percutaneously.

Slide 21:

Again, we see shrinkage of the lesion, decease in Hounsfield units. Using our criteria for a successfully treated lesion we have one failure. We have three people in the indeterminate category, which are not growing. In the 50 watt we saw a number of six indeterminates which grew, and we had patchy tumor and patchy necrotic tissue. These have not grown yet, and we are continuing to follow them.

Slide 22:

This is one of the central tumors, what we call the medullary tumor. A is pretreatment and B is post treatment, and looks to be dead.

Slide 23:

This is another tumor on the lip there, which looks well treated.

Slide 24:

Ultrasound is very useful and essential, and that has been one of the big things that has been helpful, having the radiologists there, because we make sure we have our needles very well placed in multiple planes.

Slide 25:

You can see the ultrasound here. It is a nice visualization. You put the needle in.

Slide 26:

You see the tumor shrink, you see some normal kidney shrink, and it is very rewarding. You see the whiteout of the lesions. Some people have reported waiting for the micro bubbles to go away, to be reabsorbed. We have not had any luck for that. We have waited for 15 minutes and haven't seen resorption, so we have stopped trying to do that.

Slide 27:

This is our one failure in this group, who failed at 19 months after treatment. We usually see people two or three months, and then every six months thereafter, looking for failure. Our latest failures have been at 19 months in the 50 watt and in this 200 watt group.

This is the ultrasound during treatment. This is before treatment and this is after RFA, and you can see there is still some persistent stuff in the patient recurring right next to the hilum, which is right in that area, so we assume it is related to that.

Slide 28:

Generally, we didn't have a lot of complications. We saw some hematuria, cellulitis in the patients. Some of the patients with hematuria also had some sterile pyuria. The renal function again with serum creatinine, creatinine clearance. We saw no change pre and post treatment. With differential renal scan, we are starting to see some subtle changes in renal function in those patients.

One patient who was operated on previously did not want to have an open operation, and wanted us to treat her with RFA. Her ureter was densely adherent to the kidney. I think at the time of the procedure we thought we were going to burn the ureter, and we did. We went along with the patient's wishes to try to avoid it, and she had a UPJ repair later.

Slide 29:

So in summary, we think this is a technology which is in an intermediate phase of evaluation. We are past the early devices, which were not as successful. We are on higher wattage devices, which are starting to damage the kidney a little bit, but not probably clinically significantly. We are seeing responses, and we need more follow up to see how durable the responses we are seeing are, because some of the recurrences can be fairly late.

That's all.

Thank you.