Yttrium-90 Microsphere Radioembolization of Liver Malignancies

Abstract

Transarterial radioembolization (TARE) with yttrium 90 microspheres is an increasingly popular therapy for both primary and secondary liver malignancies. TARE entails delivery of b-particle brachytherapy and embolization of the tumor vasculature.(Singh and Anil, 2012) Hepatocellular carcinoma (HCC) is one of the most common malignant tumours worldwide. Egypt has the highest prevalence of HCV in the world and the prevalence of HCC is increasing in the last years. (Shaker et al., 2013) The diagnosis of HCC is based on either a tissue specimen or on very specific CT/MRI findings. Pathological diagnosis of HCC requires a biopsy of the tumor or a resection specimen. Stromal invasion or tumor cell invasion into the portal tracts or fibrous septa, defines HCC and is not present in dysplastic lesions . Immunostaining for GPC-3, HSP70, and GS is recommended to differentiate high grade dysplastic nodules from early HCC . Non-invasive diagnosis is based on imaging techniques and characterized by identification of the typical radiological hallmark of HCC.(Jain, 2014) Recent advances in imaging techniques, such as computed tomography (CT), magnetic resonance imaging (MRI), ultrasound (US), positron emission tomography (PET), and integrated PET-CT imaging, have increased our ability to detect and characterize focal liver lesions.(Choi, 2006) Hepatic vascularisation is complex, and anatomic variations are very frequent. Nevertheless, it is essential to be able to recognize this both in conventional imaging (planning of the procedure) and on angiography for any hepatic procedure by endovascular route. This perfect understanding helps optimize the treatment and avoids the ‘‘non targeted’’ arteries, responsible for sometimes severe complications.(Favelier et al., 2014) Radioembolization has been shown to be an effective treatment for patients with liver malignancies. Preprocedure planning and meticulous mesenteric angiography is of paramount importance to determine the safest and most effective treatment strategy. Identifying anatomic variants, isolating the hepatic circulation and prophylactic embolization requires attention to detail that has not been a focus of TACE or TAE.(Salem et al., 2007) A retrospective study by Peterson et al. provides a comprehensive analysis of early and late complications associated with 90Y microsphere radioembolization to assist clinicians in counseling their patients regarding this potential treatment option. Although many patients experienced symptoms of early postradioembolization syndrome, these symptoms were self-limited and generally occurred within the first 2 weeks after treatment. The cumulative incidence of late Grade 3 or 4 early toxicity was 8% and no Grade 5 toxicity occurred, suggesting that 90Y microsphere radioembolization is well tolerated. Future investigations should focus on prospective collection of toxicity information to provide more accurate estimates of complication rates and should use larger samples to better delineate patient characteristics and treatment variables that are associated with an increased risk of complications.(Peterson et al., 2013) Advancements in radioembolization have allowed the evolution of a therapy that is well tolerated by the patient, may be as effective as other alternatives available, and may have more widespread adoption once additional studies have been performed. Finally, the toxicity profile of all hepatic embolization therapies irrespective of their nature (embolic, radiation, drug-eluting) can be improved significantly by applying the angiographic principles described in this technical manuscript.(Salem et al., 2007)