High-dose hypofractionated X-ray radiotherapy for hepatocellular carcinoma

14:40-15:00, Room 101 (101講堂)

Abstract - 

High-dose hypofractionated X-ray radiotherapy for hepatocellular carcinoma

As radiotherapy (RT) is being integrated into multi-modality treatment for hepatocellular carcinoma (HCC), either photon (X-ray) therapy or particle (proton and carbon) therapy is used. X-ray therapy is widely accessible and reimbursed by the insurance system, and is composed of mature technology and full-option image guidance. Particle therapy with dosimetric sparing advantage is still evolving for the comprehensive delivery and imaging functions, but short of insurance reimbursement. Despite the acceptable local control in the irradiated hepatic tumor, a certain proportion of patients develop intrahepatic and/or extrahepatic metastasis. The early published series using 1.8-2 Gy per fraction reported more than half of patients with metastasis out of RT field. Such an RT associated metastasis, especially in the liver, compromises the hepatic reserve and offsets the survival. Rare complete response and most partial response or stable disease of irradiated tumors indicate the sublethal effect of long fractionated RT. Higher-intensity radiation by higher dose-per-fraction and fewer fraction-number hypofractionated RT (2.5-5 Gy per fraction for 10-20 fractions) or ultra-short stereotactic body radiation therapy (SBRT) (6-10 Gy per fraction for 3-6 fractions) demonstrates improved control of irradiated tumor and reduced incidence of out-of-field metastasis. The comparative effect of large retrospective studies on SBRT showed the non-inferior control of small-/medium-sized HCC compared with RFA. Only one randomized trial on patients HCC with major vascular invasion treated with chemoembolization in combination with SBRT showed the superior survival to sorafenib. The developing radiation sensitizers, such as histone deacetylase inhibitor, aurora kinase inhibitor and hopefully immunotherapy may shed light in potential lethal effect on HCC when combined with RT. More cooperative groups for multi-center trials are needed to form the consensus and establish evidence.