Efficacy and safety of carbon-ion radiotherapy for large hepatocellular carcinoma (diameter ≥ 10 cm)

Background Large, unresectable hepatocellular carcinoma (HCC) remains incurable, and the risk of radiation-induced liver damage makes definitive radiotherapy challenging. We aimed to evaluate the efficacy and safety of carbon-ion radiotherapy (CIRT). Methods We retrospectively analyzed records of 33 CIRT-treated patients with HCC (diameter ≥ 10 cm) at Osaka Heavy Ion Therapy Center. Rates of local control (LC), progression-free survival (PFS), and overall survival (OS) were calculated using the Kaplan–Meier method. Toxicities were evaluated according to the Common Terminology Criteria for Adverse Events v5.0. Results The median tumor diameter was 11 (range: 10–18) cm. Stage IB was the most common disease stage, and alcoholic liver disease was the most common underlying condition. The relative biological effectiveness-weighted dose was 60 Gy/4 fractions, 67.2 Gy/12 fractions, and 60 Gy/12 fractions in 19, 8, and 12 patients, respectively. Based on pretreatment liver function, 27 and 6 patients were categorized as Child–Pugh classes A and B, respectively. The median follow-up period was 15.1 (range: 2.8–54.0) months. The 1-year LC, PFS, and OS rates were 85.9%, 30.0%, and 74.8%, respectively. Grade ≥ 3 toxicities included pleural effusion in 2 patients (6%) and hepatic failure, heart failure, bile duct stricture, and biliary tract infection in 1 patient (3%) each. No grade ≥ 4 toxicities occurred. Radiation-induced liver damage, defined as a Child–Pugh score increase ≥ 2 points from the pretreatment baseline, occurred in 5 patients (15%). Conclusions CIRT for large HCC (≥ 10 cm) was effective in the short term, with acceptable toxicities. Trial registration: Not applicable.