Radiotherapy as valid modality for hepatocellular carcinoma with portal vein tumor thrombosis

Abstract

Although the current standard treatment for hepatocellular carcinoma (HCC) with portal vein tumor thrombosis (PVTT) is sorafenib, many previous studies have established the need for a reliable local modality for PVTT control, which is a major cause of liver function deterioration and metastasis. Additionally, there is growing evidence for the prognostic significance of PVTT classification according to the location of tumor thrombosis. Favorable outcomes can be obtained by applying local modalities, including surgery or transarterial chemoembolization, especially in second-order or distal branch PVTT. Rapid control of PVTT could maintain or improve liver function and reduce intrahepatic as well as distant metastasis. Radiotherapy (RT) is one of the main locoregional treatment modalities in oncologic fields, but has rarely been used in HCC because of concerns regarding hepatic toxicity. However, with the development of advanced techniques, RT has been increasingly applied in HCC management. Randomized studies have yet to definitively prove the benefit of RT, but several comparative studies have justified the application of RT in HCC. The value of RT is especially noticeable in HCC with PVTT; several prospective and retrospective studies have reported favorable outcomes, including a 40% to 60% objective response rate and median overall survival of 15 mo to 20 mo in responders. In this review, we evaluate the role of RT as an alternative local modality in HCC with PVTT.

Keywords: Alternative; Hepatocellular carcinoma; Local modality; Portal vein tumor thrombosis; Radiotherapy.

Figure 1

Classification of portal vein tumor thrombosis. PVTT is classified into four categories according to the site of tumor thrombus as suggested by the Liver Cancer Study Group of Japan. PVTT: Portal vein tumor thrombosis.

Figure 2

Radiation dose distribution according to radiotherapy technique. More conformal dose delivery to the main mass and tumor thrombosis with a reduced liver dose is achievable with 3D-CRT, IMRT, and SABR, as well as to an even greater extent with proton beam RT. 3D-CRT: Three-dimensional conformal RT; IMRT: Intensity-modulated RT; SABR: Stereotactic body ablative RT. RT: Radiotherapy technique.

Figure 3

Suggested local treatment modalities for hepatocellular carcinoma with portal vein tumor thrombosis according to portal vein tumor thrombosis classification. To rapidly eliminate tumor thrombosis, RT with or without TACE could be considered, except in the case of technically resectable Vp1/2 disease with a favorable prognosis. HCC: Hepatocellular carcinoma; PVTT: Portal vein tumor thrombosis; RT: Radiotherapy; TACE: Trans-arterial chemoembolization.