Principles of Pressure Directed Therapy with Y90 Radioembolization in Hepatocellular Carcinoma (HCC)

[Dr. Nainesh Parikh]
“...any time that we're talking about unresectable liver disease, especially HCC, the theory is that the blood flow distribution for these tumors are predominantly arterial, rather than portal venous. So, in these patients, we think about how to take advantage of that fact, and deliver therapy through the artery.

The way we always explain to patients is you've got three choices: you've got radioactive material that's loaded on small spheres that gets delivered to places with increased blood flow; you've got chemotherapy, that's loaded on small pieces of glass, or spheres as well, that also goes predominantly to where the blood flow takes it; and then you've got just spheres in and of themselves, without anything loaded, that goes to where the blood flow takes it.

And each of those three, while they are all predicated upon the blood flow, they all have different outcomes: so for radioembolization, our goal is simply to deliver the radioactive dose to the tumor. And when we think about delivering radioembolization, or Y90 as sometimes people will call it, standing for Yttrium-90 - what it requires is a mapping angiogram, at least for us, and that's one procedure where you go and literally map out the vasculature to the tumors that you're trying to treat.

The most traditional sense is that, if it's Bilobar Disease - there are two arteries that supply the left lobe of the liver, and the right lobe of the liver, and so what you'll do is just treat the right lobe with a certain treatment, and then you'll let the patient heal; and six weeks later, you'll treat the left lobe. And then that's kind of how the practice started....

...the end point that we're trying to achieve is simply the delivery of the entire calculated dose. I'll just say a note on dose calculation: there [are] various ways to calculate the appropriate radioactive dose for HCC, but for the most part the goal is simply to deliver the entire dose into each of those arteries supplying the lobe of the tumor.”

[Dr. Nainesh Parikh]
“...Charlie and I have been talking about how pressure-directed therapy started, and I think here would be an appropriate nod to the fact that it actually started as an antireflux device, the Surefire system in particular.

There have since been the advent of other catheters that are speaking more toward pressure-directed therapy, but just for that person who might not know the nuanced differences between what we're talking about for all these catheters, Surefire in particular started out as an antireflux device. So, the whole point was to protect against non-target embolization of specifically other organs.

Now what research has found, and I think is promising, is that when you use these antireflux devices, you actually improve perfusion through the tumor, there are perfusional changes that occur when normal systole and diastole are altered by any antireflux device such as the Surefire. Balloon occlusion devices also do the same, or similar thing.”