Radiation Segmentectomy and Radiation Lobectomy: An Interview With Siddharth Padia, MD

Dr Padia spoke with IO Learning about his findings on making unresectable patients resectable, success in using a newer technique, and the future of tumor ablation. 

Can you tell us about making unresectable patients resectable?

There are a significant number of patients who could theoretically be resectable; however, when surgeons remove the right hepatic lobe, there’s not enough of a left hepatic lobe to sufficiently carry all the function. The goal of radiation lobectomy has been to make these patients surgically resectable by growing the left hepatic lobe. By delivering a relatively high dose of Y-90 to the right lobe, the right lobe will then atrophy, causing the left lobe to hypertrophy. Then, patients could be eventually surgically resectable. The additional advantage is that one is also treating the cancer at the same time.

What are the potential risks?

Complications can be minimized if the appropriate patients are selected. Complications occur when, for example, patients have insufficient or poor baseline liver function at the time of treatment. Then, there is a risk of liver decompensation or liver failure, so it’s important to properly select the patients up front. 

Are there any gray areas regarding patient selection for radiation segmentectomy and lobectomy for Y-90?

There are a couple of factors that may be gray areas. One is the patient with borderline liver function, someone who does not have optimized liver function but is worsening. The other is what’s called a patient’s performance status — just how functional they are. If they have a compromise in their performance status, the overall benefit of this therapy is limited.

Do radiation lobectomy patients have to be surgical candidates?

Initially, when I referred to patients having to be appropriately selected, it was a joint decision between interventional radiologists and surgeons that they should eventually get a surgical resection. We are now finding that we’re able to do this even if they don’t get surgical resection in the future. We’re still getting long-term tumor response by doing the same treatment strategy, often without the need for surgery.

Why aren’t these patients surgical candidates?

These patients may be on the older side or have poor performance status. Those are typically the patients that we see.

Your presentation at CIO 2019 also covered segmental hepatocellular carcinoma (HCC) Y-90 versus transarterial chemoembolization (TACE). Can you tell me a little bit more about those concepts?

Basically, the concept in radiation segmentectomy is to deliver a very high dose to very small areas of liver. The conventional approach was to deliver lower doses to large areas of liver, so we’ve changed the treatment.

How recently did the treatment algorithm change?

This changed over the last several years, but the data matured in the last 2-3 years. The data have shown that when we’re delivering high doses of radiation via Y-90 to small areas, our tumor kill rates are in excess of 90%. Over several years, the probability of the tumor coming back is extraordinarily low. The rates are almost essentially equivalent to other therapies, which are considered “curative,” such as surgical resection or ablation.

Is there anything stopping this approach from eventually being considered curative? 

I don’t think there’s actually anything stopping it from being considered curative because the cure rates are the same as other potentially curative modalities. We had compared it to transarterial chemoembolization, and found out that the rates of tumor kill were much higher with the segmentectomy approach versus the selective chemoembolization approach. Also, we were able to treat patients with larger tumors, more aggressive tumors, faster growing tumors, people with compromised liver function, and most importantly, the complication rates and the adverse events rates were extraordinarily low.

When were the results and complication rates measured?

The complication rates were measured out at 3 months, but we were looking at the overall results over 3 to 4 years. 

Do you have any ongoing research?

Right now, we’re about to publish our experience looking at Y-90 radiation segmentectomy for liver metastases because most of the data to date have been for hepatocellular carcinoma.

What were some of the learning points from the cases you mentioned in your presentation? 

There was a case of a young gentleman with a hepatocellular carcinoma where ablation, which is considered curative, could have been performed, but would have been extraordinarily challenging. With a segmentectomy approach, the procedure itself was very straightforward. He had no complications, had a complete tumor kill at 2 years, and then was successfully transplanted.

Are there any controversies in this area of interventional oncology?

I think that the controversies lie in the fact that there is still debate as to whether this or ablation is considered a superior treatment strategy. There are concerns that radiation segmentectomy is not widely adaptable among institutions.

Is that because of equipment or resources?

Technique. There’s concern that people can’t do it, but I don’t necessarily agree with that. All procedures are complicated. Everything has a learning curve, and I think that with meticulous technique and patience, most interventional radiologists can learn how to do it.

In this procedure, is there less of a margin for error?

If you’re slightly off, you can get a suboptimal result or just a suboptimal tumor kill. That being said, we’ve spent years developing this technique and we’ve published on how to do it. We’ve delineated how to do the technique very clearly. I think that if people are patient and take the time and effort to do it, most interventional radiologists can achieve the same results. As long as they’re comfortable with doing the Y-90 procedure in general, I think that most people can do this. They can learn from papers, phone calls, presentations, and going to conferences. I don’t think it needs on-site training.

Any final thoughts?

I think that where traditionally Y-90 radioembolization was used for patients with advanced or end-stage cancer, we are now using it to make tailored approaches earlier in a patient’s disease process. As a result, we’re achieving much better long-term outcomes.

Disclosure: Dr Padia is a scientific advisor for BTG International, AngioDynamics, ICON Research, and Bristol Myers Squibb; he reports research support from BTG International, Boston Scientific.

Address for correspondence: Siddharth Padia, MD, Vascular and Interventional Radiology, UCLA Medical Center, 757 Westwood Plaza, Suite 1501, Los Angeles, CA 90095. Email: spadia@gmail.com