Radiofrequency ablation for patients with liver metastases

I began studying this modality in the laboratory in 1993 and in clinical trials in 1996. It’s a technique that allows us to treat tumors that cannot be resected because they were either in a bad location or bilobar.

We’ve now shown that you can safely do a combination of resection of the dominant or large tumors and then ablation of the smaller tumors in the opposite lobe without an increase in the complication rate. Long-term outcomes data with that type of aggressive approach indicate good results with patients surviving for longer periods of time (Pawlik 2003).

Radiofrequency ablation has a low rate of side effects; our group has shown a less than 10 percent complication rate (Curley 2004; [2.1]). In addition to the early complications (eg, abscess in the ablated lesion or bleeding from the needle track), some patients develop late complications such as bile duct strictures or fistulae.

Others patients develop bilomas, which are large collections of bile in the liver. Fortunately, those types of side effects have a low incidence — only about 2.5 percent of patients develop long-term side effects or toxicity (Curley 2004).

Radiofrequency ablation in clinical practice

This approach is now widely used in the United States. It’s a technique that is being used by surgeons and interventional radiologists. The incidence of local recurrence — what I call incomplete treatment — is much lower in the hands of surgeons, primarily because we do it intraoperatively either with laparoscopic or open ultrasound guidance.

It is important to carefully evaluate the indications for radiofrequency ablation. I use it only in patients who can be treated with curative intent alone or combined with surgical resection. I’ve seen patients who have undergone radiofrequency ablation for palliation of symptoms. That may be useful in select settings, but it has to be used judiciously.

In general, if the tumor can be surgically resected, that’s what I do. In patients with colorectal cancer, with the techniques we now have available, less than five percent of patients require blood transfusions. Historically, liver resections were associated with a high risk of problems. At MD Anderson, the mortality rate is less than one percent and the complication rate is less than 30 percent.

Maximizing the benefit of radiofrequency ablation

We’ve seen the greatest benefit from ablation in two patient populations. The first is the patient with disease that is metastatic to the liver in a bad location (eg, nestled on the vena cava or under the hepatic veins). Surgical data demonstrate that unless you can perform a resection and obtain a tumor-free margin, you do not provide any benefit to the patient.

A tumor in that location frustrates surgeons because we know we’re not going to be able to obtain a negative margin. In that patient population, we can demonstrate a benefit by performing tumor ablation with either radiofrequency or microwave.

The other patients who will benefit from ablation are the patient with hepatocellular cancer. The vast majority of them have underlying liver disease, such as cirrhosis from chronic hepatitis B or C infection, and they definitely have some element of hepatic dysfunction.

Those patients are clearly at a high risk of liver failure and death after a resection. Because we have such a high demand for liver transplants in this country, many of them aren’t going to be candidates for a transplant because an organ will not be available.

We’ve just published our data from MD Anderson on radiofrequency ablation for early-stage hepatocellular cancer, and the results are actually better than the results after resection but not quite as good as the results after transplant. We’re now using radiofrequency ablation as a bridge to transplantation in select patients.

Chemotherapy and radiofrequency ablation in patients with liver-only metastases

In patients with colorectal cancer, using radiofrequency ablation alone without any additional systemic or regional chemotherapy offers about a 15 percent to 20 percent probability of cure for unresectable disease. That’s based on our own results at MD Anderson where our four-year overall survival rate is about 22 percent. Certainly, a subset of patients will be alive and without disease at four years (Abdalla 2004).

Adding chemotherapy to radiofrequency ablation — either as neoadjuvant or adjuvant therapy — nearly doubles the overall survival to 35 percent to 40 percent. In contrast, if those patients were treated only with systemic chemotherapy, that number would be less than 10 percent (Abdalla 2004). In the past, it would have been less than one percent or two percent, but the response rates are higher, with some of the FOLFOX regimens and the addition of drugs like bevacizumab.

Some patients will refuse chemotherapy or will have had previous chemotherapy and do not want more. That doesn’t mean we won’t offer them a resection. We know that’s going to give them their highest probability of long-term survival, but we tell them they’re going to need to be followed closely.

NSABP-R-04: Capecitabine versus continuous infusion 5-FU as neoadjuvant therapy for rectal cancer

A large volume of Phase II data demonstrates that capecitabine is similar to infusional 5-FU. While it’s a good idea to perform the NSABP study, I’m not sure that we necessarily need it. It’ll be interesting to see how that study accrues. In this country, physicians are rapidly adapting regimens based on Phase II data, but it’s become a bit of a minefield because so many regimens are available. I think R-04 is going to be sort of a “thanks for confirming what we already suspected was true” type of study.

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Steven A Curley, MD Dr Curley is a Professor of Surgical Oncology and Chief of Gastrointestinal Tumor Surgery at The University of Texas MD Anderson Cancer Center in Houston, Texas.