A retrospective report from Japan. Eighty-three patients with HCC underwent particle therapy including proton beam radiation in 58 patients and carbon ion radiation in 25 patients were analyzed. Patients were categorized into early-stage HCC (single HCC measuring ≤3 cm, Barcelona Clinic Liver Cancer [BCLC] stage 0 or A) (group A, n = 30), those with intermediate-stage HCC (HCCs measuring ≥3 cm but inoperable or multinodular and transcatheter arterial embolization [TACE]-refractory, BCLC stage B) (group B, n = 31), and those with advanced-stage HCC (HCC with portal invasion or extrahepatic metastasis) (group C, n = 22).

This study reported that the rates of local control of the target tumor at 1 year and 2 years were 86.3 and 84.8%. The overall survival rates at 1, 2, and 3 years were 83.0, 65.6, and 55.1%, respectively. Patients in group A showed the best survival rates (100.0% at 1 year and 85.9% at 2 years). The 1-year survival rate was poor in group C (63.6%) despite a good local tumor control rate of 74.7%. The overall survival rates were significantly better in groups A and B than in group C. This study concluded that the local control rates after PRT were sufficiently high compared to TACE or sorafenib. Thus, PRT should be adopted for patients with difficult-to-treat HCC in the early and intermediate stages.