Identifying Good Candidates for Histotripsy to Treat Liver Tumors

There are some factors that make some patients better candidates for histotripsy than others and some instances in which histotripsy would not be a good option, said Shaun P. McKenzie, MD, FACS, a surgical oncologist with Texas Oncology. In addition, he said this treatment is just another tool in addition to what oncologists already have to treat patients and is not replacing the standard of care.

Transcript has been edited; captions are auto-generated.

Transcript

In addition to being able to see the tumor on ultrasound and the location of it, what other characteristics do you look for to identify a good candidate for histotripsy?

I think one is, we want to see relatively normal liver function, right? Like the one patient I mentioned. You don't want to do this to someone who's already approaching liver failure, right? That's one thing. I think the other thing we also talked about before is they have to be at least healthy enough to undergo general anesthesia. If you say, “Well, I wouldn't remove this tumor, because this patient's lungs are too bad,” well, but you're going to still put them under general anesthesia.

Then I think the other thing is, this is a liver-directed treatment, and if a patient has cancers in other locations—say their lungs or their bones or somewhere else—to put them through this procedure and not have good control of the cancer outside the liver does not make sense, right? We prefer for their disease to only be in the liver with this treatment, but if they do have disease outside the liver, their other treatments have to be controlling that disease very well. That's a big point, because I've had a few patients who have approached us for this treatment, but they had lung metastases that were growing. And I said, “Well, wait a minute now, we gotta think of all of you, not just part of you.” That's an important thing.

I think location of tumors is always critical. One of the things that we haven't really talked about is, we see opportunities to even use this treatment to help make surgery safer. For example, if I have a patient who has a tumor that on one side is attached or wrapped around a critical blood vessel, could I use histotripsy to treat that edge and then remove the tumor? Because that's an important thing. Size is another thing. This treatment is best for tumors under 4 centimeters. You can try overlapping treatment zones for bigger tumors, but the reality is—and all of the ablative treatments we've developed so far have been the same—as you get larger than 3 to 5 centimeters, the likelihood that an ablative treatment is going to be completely effective goes down. You have to take that into consideration when you're considering a treatment like this.

Anything else you want to tell people about histotripsy?

This is another treatment modality that works in concert with everything else we have so far. This is not something that we've developed in lieu of everything else. It's something that we will always consider if and when appropriate. But at the end of the day, a patient with tumors in the liver needs a multidisciplinary team of physicians reviewing their case. It requires a cancer surgeon who has specialty in liver tumors, a medical oncologist who has specialty experience in the tumor that are being treated, whether they started in the liver or they've spread there, and then sometimes it even requires interventional radiologists and radiation oncologists.

I think the importance is, this treatment has not changed the standard of care for cancer, which is cancer requires a multidisciplinary approach.