Chemoembolization and radioembolization

Abstract

Chemoembolization and radioembolization are at the core of the treatment of patients with hepatocellular carcinoma who cannot receive potentially curative therapies such as transplantation, resection or percutaneous ablation. They differ in the mechanism of action (ischaemia and increase cytotoxic drug exposure for chemoembolization, internal irradiation for radioembolization) and may target different patient populations. Chemoembolization with cytotoxic drug-eluting beads is a more standardized although not necessarily more effective way of performing chemoembolization. Cytoreduction is achieved in most patients but complete tumor ablation may be achieved and lead to extended survival. Grade 1 level of evidence support the use of chemoembolization for the treatment of patients in the early and intermediate stages while grade 2 evidence supports the use of radioembolization for the treatment of patients in intermediate to advanced stages. Selecting the best candidates for both techniques is still a work in progress that ongoing clinical trials are trying to address.

Introduction

Most patients with hepatocellular carcinoma (HCC) are diagnosed at late stages, when curative surgical treatments cannot be applied [1]. According to guidelines from the European and American Association for the Study of the Liver [2], [3], the BCLC classification with its five tumor stages should be used for tumor staging. Surgery by means of resection or transplantation and percutaneous ablation are restricted to the very early or early tumors (stage 0 and A) while intraarterial and systemic therapies are recommended for intermediate and advanced tumors, respectively (stages B and C) [4]. However, up to 50% of patients cannot receive the recommended treatment modality because of availability, technical issues, age or comorbidities [5] and guidelines are evidence-based flexible frameworks on which individual therapeutic strategies can be built upon by multidisciplinary teams [2]. The most common intraarterial techniques used in HCC treatment are transarterial chemoembolization (TACE) with or without drug-eluting beads (DEB) and radioembolization (RE). They differ in mechanism of action, technique and typical patient population, which translates into differences in patient monitoring, complications and outcomes. And they are all widely accepted for treating appropriately selected HCC patients.