Radioembolization with Yttrium-90 microspheres in hepatocellular carcinoma: Role and perspectives

Abstract

Transarterial radioembolization (TARE) is a form of brachytherapy in which intra-arterially injected yttrium-90-loaded microspheres serve as a source for internal radiation purposes. On the average, it produces disease control rates exceeding 80% and it is a consolidated therapy for hepatocellular carcinoma (HCC); however, current data are all based on retrospective series or non-controlled prospective studies since randomized controlled trials comparing it with the other liver-directed therapies for intermediate and locally advanced stage HCC are still underway. The data available show that TARE provides similar or even better survival rates when compared to transarterial chemoembolization (TACE). First-line TARE is best indicated for both intermediate-stage patients (staged according to the barcelona clinic liver cancer staging classification) who have lesions which respond poorly to TACE due to multiple tumors or a large tumor burden, and for locally advanced-stage patients with solitary tumors, and segmental or lobar portal vein tumor thrombosis. In addition, emerging data have suggested the use of TARE in patients who are classified slightly beyond the Milan criteria regarding radical treatment for downstaging purposes. As a second-line treatment, TARE can also be applied in patients progressing to TACE or sorafenib; a large number of phase II/III trials are ongoing with the purpose of evaluating the best association with systemic therapies. Transarterial radioembolization is very well tolerated and has a low rate of complications which are mainly related to unintended non-target tissue irradiation, including the surrounding liver parenchyma. The complications can be additionally reduced by accurate patient selection and a strict pre-treatment evaluation including dosimetry and assessment of the vascular anatomy. Since a correct treatment algorithm for potential TARE candidates is not clear and standardized, this comprehensive review analyzes the best selection criteria for patients who really benefit from TARE and also the new advances of this therapy, which can be a very important weapon against HCC.

Keywords: Hepatocellular carcinoma; Radioembolization; Yttrium-90.

Figure 1

Treatment with Yttrium-90 and response of infiltrative hepatocellular carcinoma. A and B: The pretreatment computed tomography (CT) showing infiltrative hepatocellular carcinoma in the IV segment with associated tumor thrombosis of the left portal branch as visualized in the arterial phase and in the portal-venous phase; C: The pretreatment angiogram carried out with selective catheterization of the left hepatic artery, arising from the left gastric artery, confirms the hypervascularization of the venous thrombus; D: The pretreatment 99mTc-MAA single photon emission computed tomography images showing the corresponding uptake of MAA in the region of interest (tumor thrombus); E and F: The CT performed 1 mo after treatment showing both a significant decrease of the enhancement of the portal venous thrombus and a reduction in the enlargement of the portal branch as a sign of response, better visualized at 1 year (G and H). Note the significant “shrinkage” of the left lobe and the compensatory hypertrophy of the contralateral hepatic lobe. 99mTc-MAA: 99mTc labeled macroaggregated albumin.