Published online Dec 21, 2018. doi: 10.3748/wjg.v24.i47.5331
Peer-review started: September 19, 2018
First decision: October 16, 2018
Revised: October 24, 2018
Accepted: November 2, 2018
Article in press: November 2, 2018
Published online: December 21, 2018
Various therapeutic modalities including radiofrequency ablation, cryoablation, microwave ablation, and irreversible electroporation have attracted attention as energy sources for effective locoregional treatment of hepatocellular carcinoma (HCC); these are accepted non-surgical treatments that provide excellent local tumor control and favorable survival. However, in contrast to surgery, tumor location is a crucial factor in the outcomes of locoregional treatment because such treatment is mainly performed using a percutaneous approach for minimal invasiveness; accordingly, it has a limited range of ablation volume. When the index tumor is near large blood vessels, the blood flow drags thermal energy away from the targeted tissue, resulting in reduced ablation volume through a so-called “heat-sink effect”. This modifies the size and shape of the ablation zone considerably. In addition, serious complications including infarction or aggressive tumor recurrence can be observed during follow-up after ablation for perivascular tumors by mechanical or thermal damage. Therefore, perivascular locations of HCC adjacent to large intrahepatic vessels can affect post-treatment outcomes. In this review, we primarily focus on physical properties of perivascular tumor location, characteristics of perivascular HCC, potential complications, and clinical outcomes after various locoregional treatments; moreover, we discuss the current status and future perspectives regarding percutaneous ablation for perivascular HCC.
Core tip: Recently safety concerns have been raised regarding the risks of radiofrequency (RF) ablation for perivascular hepatocellular carcinomas (HCCs), due to the risks of ischemic complications and intravascular tumor spread during treatment. To overcome these potential risks, a modified RF ablation technique, cryoablation, combined treatment with transarterial chemoembolization, or microwave ablation could be problem-solving tools for the treatment of perivascular HCCs. However, the effectiveness of these techniques should be validated with further prospective studies due to the lack of current evidence.