Introduction

Primary and secondary liver tumors are a common cause of morbidity and mortality around the world. While curative therapies for some of these cancers exist – hepatocellular carcinoma (HCC) can be treated with partial hepatectomy or liver transplantation – many patients are ineligible for curative liver resection due to the advanced stage of their cancers; furthermore, widespread implementation of liver transplantation is prevented by a shortage of donor organs. The same is true for patients with metastatic colorectal or neuroendocrine tumors. Due to these shortcomings, various palliative therapies have been advanced in the management of hepatic neoplasms. These include systemic chemotherapy, radiation therapy, and local and regional percutaneous modalities. The latter group comprises both ablative techniques (chemical and thermal), and the intra-arterial embolotherapies.

Unlike healthy hepatocytes, which are supplied largely by the portal venous circulation, both primary and secondary liver tumors receive their vascular supply principally from the hepatic artery. Thus, occlusion of the hepatic artery would be expected to lead to ischemic necrosis of tumor cells while selectively sparing the native liver. This principle has been exploited in the development of bland transarterial embolization (TAE) and transarterial chemoembolization (TACE). In both of these approaches, the branches of the hepatic artery that supply the tumor are occluded with embolic particles. For chemoembolization, chemotherapeutic agents are added to the embolization mixture for delivery directly into the tumor.

In principle, chemoembolization targets liver lesions by a multifaceted attack. First, embolization of the vascular supply triggers localized tissue ischemia.