Liver Cancer: Microwave Ablation and Ideal Surgical Margin

Liam Davenport

July 05, 2017

BARCELONA, Spain ― New findings regarding the treatment of hepatocellular carcinoma (HCC) include results from a study on microwave ablation (MWA) and a study regarding the ideal surgical margin.

Both studies were reported in poster presentations here at the 19th World Congress on Gastrointestinal Cancer (WCGC) and were highlighted in a discussion of notable abstracts by Chris Verslype, MD, PhD, University Hospital Gasthuisberg, Leuven, Belgium.

The use of MWA for the treatment of HCC was reported by Näık Vietti Violi from Lausanne University Hospital, Switzerland, and colleagues.

This technique has theoretical advantages over radiofrequency ablation (RFA), the researchers commented. Those advantages include shorter ablation time, higher temperature of ablation, reduction of heat-sink effect, and the ability to treat larger lesions.

However, owing to a lack of prospective studies assessing its efficacy, MWA "is still not accepted for the treatment of HCC as RFA is," they said.

MWA is not in guidelines for the management of HCC, Dr Verslype noted. His study is the first prospective, randomized controlled trial to investigate MWA vs RFA in a population of HCC patients with small lesions.

The trial was conducted in patients with chronic liver disease. Patients had ≤3 HCC lesions of ≤4 cm of BCLC (Barcelona Clinic Liver Cancer) stage 0/A and were not eligible for surgery.

A total of 152 patients were prospectively enrolled from 2011 to 2015. The final RFA group consisted in 73 patients in whom 104 lesions were ablated (11 women, 53 patients with lesions of Child-Pugh class A). The final MWA group consisted of 71 patients in whom 98 lesions were ablated (12 women, 57 patients with lesions of Child-Pugh class A).

At 2-year follow-up, there was no significant difference in rates of local tumor progression and survival between the two treatment groups, Dr Verslype noted.

With RFA, the time to progression was 15 months (SD, 7); with MWA, it was 12 months (SD, 8); p 1⁄4 0.48). The survival rate at 20 months was 88.5% in the RFA group and 88.8% in the MWA groups (p 1⁄4 0.88).

There was also no difference between the two groups in the number of patients who underwent transplant and the number of lesions for which treatment was incomplete.

Dr Verslype said that the advantage of MWA over RFA, in addition to some technical advantages, is that it can be performed percutaneously without the need for surgery and it can reach more lesions.

He added: "I really think that this is important that microwave ablation can be applied with similar confidence as radiofrequency ablation."

Ideal Surgical Margin

The other abstract that Dr Verslype highlighted, which he described as "a very important trial," presented an analysis of the risk factors for early recurrence and the ideal surgical margin for patients with HCC. The study was reported by Prof Hidetoshi Nitta from the Paul Brousse Hospital in Paris, France, and colleagues from Kumamoto University in Japan.

This analysis involved 230 consecutive patients who underwent curative hepatic resection for solitary and primary HCC between 1994 and 2014 at the Paul Brosse Hospital. Patients were followed for 5 years.

The team conducted a multivariate analysis of factors that may influence early recurrence (defined as recurrence within 8 months of hepatectomy).

The only factors found to be associated with early recurrence on multivariate analysis were alpha-fetoprotein (AFP) levels ≥100 ml (odds ratio [OR], 4.75; P < .0001) and a surgical margin <7 mm (OR, 3.26; P = .012).

In patients with both risk factors, there was a 43% probability of early recurrence, whereas for patients who had neither risk factor, the probability was only 4.6%, the reseachers reported.

They concluded that "adequate surgical margins should be more than 7 mm to prevent early recurrence." They noted that such surgical margins "are particularly valuable" for patients in whom AFP is greater than 100 ng/ml, as well as for patients with noncapsule formation or microvascular invasion.

"These results are quite remarkable," commented Dr Verslype. He noted that for patients with "excellent margin" and low AFP levels, the rate of recurrence is low, at 4.6%, whereas for patients with a small margin but high AFP levels, the rate of recurrence is much higher, at 43.0%.

"It's very interesting that if you have a wide margin, more than 7 mm, the AFP plays no role anymore," he commented. "So the surgeon can make up for poor tumor biology. This is a quite interesting message."

19th World Congress on Gastrointestinal Cancer (WCGC). Highlights of posters PD014 and PD013, presented June 30, 2017.

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