This study aimed to evaluate the initial outcomes of proton beam therapy (PBT) for hepatocellular carcinoma (HCC) in terms of tumor response and safety.

HCC patients who were not indicated for standard curative local modalities and who were treated with PBT at Samsung Medical Center from January 2016 to February 2017 were enrolled. Toxicity was scored using the Common Terminology Criteria for Adverse Events (CTCAE) version 4.0. Tumor response was evaluated using modified Response Evaluation Criteria in Solid Tumors (mRECIST).

A total of 101 HCC patients treated with PBT were included. Patients were treated with an equivalent dose of 62–92 GyE₁₀. Liver function status was not significantly affected after PBT. Greater than 80% of patients had Child-Pugh class A and albumin-bilirubin (ALBI) grade 1 up to 3-months after PBT. Of 78 patients followed for three months after PBT, infield complete and partial responses were achieved in 54 (69.2%) and 14 (17.9%) patients, respectively.

PBT treatment of HCC patients showed a favorable infield complete response rate of 69.2% with acceptable acute toxicity. An additional follow-up study of these patients will be conducted.

• Hepatocellular carcinoma
• Proton
• Radiotherapy
• Response
• Toxicity

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.

• Hepatocellular carcinoma
• Portal vein tumor thrombosis
• Radiotherapy
• Local modality
• Alternative

• Carcinoma, Hepatocellular/complications
• Carcinoma, Hepatocellular/radiotherapy
• Chemoradiotherapy
• Humans
• Liver Neoplasms/complications
• Liver Neoplasms/radiotherapy
• Portal Vein
• Radiotherapy, Intensity-Modulated
• Venous Thrombosis/therapy