Proton beam therapy in the management of hepatocellular carcinoma

Hepatocellular carcinoma (HCC) is the most common form of primary liver cancer. Photon radiotherapy shows efficacy in treating HCC but carries risks of high exit dose and radiation-induced liver disease. Additionally, HCCs with portal vein tumor thrombosis (PVTT) have a poor prognosis and are associated with higher risk of death. In recent years, proton beam therapy (PBT) has emerged as a novel treatment with the ability to downstage HCC for liver transplant (LT).

This review will provide an overview of dosimetric benefits of PBT, efficacy of PBT in treating HCC, downstaging HCC-PVTT for LT, and a comparison of PBT with other non-surgical techniques. A search of PubMed until 3 September 2024 was conducted using free search and the following keywords: hepatocellular carcinoma, proton beam therapy, portal vein tumor thrombosis, local ablative therapy, trans-arterial chemoembolization, stereotactic body radiotherapy, Y-90 radioembolization.

Various clinical trials using PBT have shown promising tumor local control and overall survival rates. PBT is mostly safe and efficacious for downstaging HCC-PVTT for LT. PBT has also been shown to be non-inferior to various other treatment modalities. Future research should focus on combinations of PBT with other modalities.