Carbon-ion radiotherapy for hepatocellular carcinoma with major vascular invasion: a retrospective cohort study

Macroscopic vascular invasion (MVI) significantly impacts survival in patients with hepatocellular carcinoma (HCC), warranting systemic therapy over locoregional therapy. Despite novel approaches, HCC with MVI has a poor prognosis compared to early-to intermediate-stage HCC. This study aimed to evaluate the safety and efficacy of carbon-ion radiotherapy (C-ion RT) for HCC characterized by MVI. This retrospective cohort study evaluated HCC patients with MVI treated using C-ion RT with a dose of 45.0–48.0 Gy/2 fractions or 52.8–60.0 Gy/4 fractions between 1995 and 2020 at our institution in Japan. We analyzed the prognostic factors and rates of local recurrence, survival, and adverse events. The local recurrence rate was determined using the cumulative incidence function, with death as a competing event. Survival rates were determined using the Kaplan–Meier method. The log-rank test for univariate analysis and the Cox proportional hazards model for multivariate analysis were used to compare subgroups. In total, 76 patients with a median age of 71 years (range, 45–86 years) were evaluated. Among them, 68 had Child–Pugh grade A while eight had grade B disease. In 17 patients, the vascular tumor thrombus reached the inferior vena cava or main trunk of the portal vein. Over a median follow-up period of 27.9 months (range, 1.5–180.4 months), the 2-year overall survival, progression-free survival, and local recurrence rates were 70.0