Proton Beam Therapy in Hepatocellular Carcinoma With Portal Vein Tumor Thrombosis

The standard treatment of advanced hepatocellular carcinoma (HCC) is sorafenib. Though the agent showed clear survival benefit in two randomized phase III trials, the benefit was modest and response rate was just a few percent. Therefore, other loco-regional modalities, like trans-arterial chemo-embolization (TACE), hepatic arterial infusion chemotherapy (HAIC), and radiotherapy (RT) were continuously tried, especially in locally advanced HCC including portal vein tumor thrombosis (PVTT). With the advancement of conformal RT techniques, RT was actively applied in HCC, especially in PVTT combined HCC. Many researchers reported that there is a relationship between RT dose and tumor response rate. RT dose, however, is frequently limited because the complications (like radiation induced liver disease (RILD), radiation induced gastro-duodenal toxicity, etc.) are also closely related with higher exposed RT dose. Proton beam has characteristic depth-dose distribution contrast to photon, the "Bragg peak". The advantage of this dose distribution could be more highlighted in HCC management, because of the weakness and maintenance importance of liver function itself in HCC patients. In fact, the superior results of proton beam therapy in HCC were constantly reported in several groups as prospectively as well as retrospectively. In those background, the investigators planned the present study to evaluate the efficacy and safety of proton beam therapy in HCC patients combined with PVTT.