Hepatocellular carcinoma (HCC) is the sixth most common cancer for both sexes or the fifth most common cancer for men worldwide with 749,000 new cases diagnosed in 2008 (5.9% of all cancers).1 Furthermore, it is the third leading cause of cancer death, responsible for 695,000 deaths in 2008.1 Although HCC is still relatively uncommon in the United States, the incidence of HCC is projected to increase, given increasing rates of chronic hepatitis C virus (HCV) infection.2 Despite the rising incidence of primary liver cancer, the vast majority of liver cancers are metastases (1.8 million cases/year) with colorectal cancer being the most common.3,4
Curative treatment for both primary liver cancer and isolated liver metastases is surgical resection. However, very few patients are considerd medically operable. As a result, several interventional oncology technologies have emerged over the past few decades for the treatment of liver cancers. Herein, we review the basic principles of transcatheter and ablative therapies currently in practice.
Hepatic arterial embolization for the treatment of hepatomas was first reported in 1977 by Yamada et al,5 with safety and efficacy demonstrated in the 1980s and more refined transarterial regimens created over the last 20 years. Today, several transarterial therapies exist with the primary goal of local control as a bridge to resection/transplantation or as a palliative treatment. These therapies exploit the dual blood supply of the liver with tumors receiving the majority of their blood supply from the hepatic artery whereas normal nontumorous liver receives the majority from the portal vein.6 Thus, by selectively occluding hepatic arterial vessels that preferentially supply the tumor, transarterial therapy begins a cascade of events leading to cell death via ischemic necrosis in tumor nodules, while selectively sparing normal tissue supplied by the portal vein. There are many flavors of transarterial therapy, which span from bland embolization with microparticles to chemoembolization with a mixture of chemotherapeutic agents, to radioembolization where resin or glass microspheres impregnated with radioactivity are delivered to the tumor.
Prior to any method of transarterial therapy, anatomic characterization with either CT or MRI is critical for preprocedure planning. Both CT and MRI are used to predict normal and/or anatomy and extrahepatic feeding vessels to help plan a general approach, which is ultimately mapped out using angiography at the beginning of each case.7,8
Until recently, portal vein thrombosis was considered an absolute contraindication to transarterial embolic therapies. However, in 2005, a small, 32 patient series demonstrated that these patients may be successfully and safely treated, without hepatic infarction or failure.9 Nonetheless, treatment in these patients should proceed with care, especially since outcome prediction remains challenging, despite the authors suggesting either the Child–Pugh class9 or the Milan criteria10 be used for this purpose.
In addition to preprocedure imaging, analysis of liver function ...