Current role of microwave ablation in the treatment of small hepatocellular carcinomas

Abstract

Percutaneous radiofrequency ablation (RFA) can be as effective as surgical resection in terms of overall survival and recurrence-free survival rates in patients with small hepatocellular carcinoma (HCC). Effectiveness of RFA is adversely influenced by heat-sink effect. Other ablative therapies could be considered for larger tumors or for tumors located near the vessels. In this regard, recent improvements in microwave energy delivery systems seem to open interesting perspectives to percutaneous ablation, which could become the ablation technique of choice in the near future. Microwave ablation (MWA) has the advantages of possessing a higher thermal efficiency. It has high efficacy in coagulating blood vessels and is a relatively fast procedure. The time required for ablation is short and the shape of necrosis is elliptical with the older systems and spherical with the new one. There is no heat-sink effect and it can be used to ablate tumors adjacent to major vessels. These factors yield a large ablation volume, and result in good local control and fewer complications. This review highlights the most relevant updates on MWA in the treatment of small (<3 cm) HCC. Furthermore, we discuss the possibility of MWA as the first ablative choice, at least in selected cases.

Short term treatment results of local ablation with water‑cooled microwave antenna for liver cancer: Comparison with radiofrequency ablation

“…However, RFA has a disadvantage, namely, if the target lesion is in the vicinity of a large vessel, RFA cannot sufficiently cauterize the tissue due to the heat sink effect; this is a phenomenon that occurs when thermal energy diffuses away from the target lesion due to blood flow in adjacent vessels (10). MWA is less susceptible to the heat sink effect because of its higher temperatures and shorter ablation times (21,22). This reduced susceptibility is ultimately due to differences in the mechanisms of action between MWA and RFA.…”

Radiofrequency Ablation and Microwave Ablation in Liver Tumors: An Update

“…When electromagnetic fields are overlapped, heating rises by N 2 , where N is the number of fields applied . Presently, RFA needs switching between electrodes when multiple antenna are applied . An essential feature when comparing RF and MWA will be the tumor's host organ and site within the organ; in fact, the tissue properties of ablated area and normal tissue are dissimilar and should be evaluated for both RF and MWA .…”

Improved survival following splenectomy combined with curative treatments for hepatocellular carcinoma in Child B patients: A propensity score matching study

“…10,36 For small liver tumors located deep in the liver parenchyma or the center of the liver, local ablation provides an alternative curative treatment option, achieving comparable oncological outcomes but remarkable low complication rates. 18 Some patients with small tumors located on the peripheral surface of the liver are also recommended for liver resection instead of local ablation. In the present study, most patients underwent liver resection, except for some patients with tumor size <3 cm and multiple tumors that were not considered candidates for liver resection.…”

“…7,8,16,17 For single tumor or multiple small tumors that could not be a candidate for liver resection, local ablation achieved comparable survival outcomes. 18 These surgical treatments (liver resection or local ablation) provide potential curative therapies for patients with HCC and Child grade B liver function that could not undergo liver transplantation.…”