Proton Beam Therapy for Hepatocellular Carcinoma: Multicenter Prospective Registry Study in Japan

IntroductionA prospective multicenter registry study was started in May 2016 in Japan to evaluate the efficacy and safety of proton beam therapy (PBT) for hepatocellular carcinoma (HCC).MethodsPatients who received PBT for HCC from May 2016 to June 2018 were registered in the database of the Particle Beam Therapy Committee and Subcommittee of the Japanese Society for Radiation Oncology (JASTRO). Overall survival (OS), progression-free survival (PFS) and local recurrence were evaluated.ResultsOf the 755 registered cases, 576 with initial PBT and no duplicate cancer were evaluated. At final follow-up, 322 patients were alive and 254 had died. The median follow-up period for survivors was 39 months (0-58 months). The median OS time of the 576 patients was 48.8 months (95% CI 42.0-55.6 months) and the 1-, 2-, 3- and 4-year OS rates were 83.8% (95% CI 80.5-86.6%), 68.5% (64.5-72.2%), 58.2% (53.9-62.2%), and 50.1% (44.9-55.0%), respectively. Recurrence was observed in 332 cases, including local recurrence in 45 cases. The median PFS time was 14.7 months (95% CI 12.4-17.0 months) and the 1-, 2-, 3- and 4-year PFS rates were 55.2% (95% CI 51.0-59.2%), 37.5% (33.5-41.5%), 30.2% (26.3-34.2%), and 22.8% (18.5-27.4%), respectively. The 1-, 2-, 3- and 4-year OS rates were significantly higher for tumor size <5 vs. 5-10 cm (p<0.001) and <5 vs. ≥10 cm (p<0.001); Child-Pugh score A/B vs. C (p<0.001); and distance of the tumor from the gastrointestinal tract <1 vs. 1-2 cm (p<0.008) and <1 vs. >2 cm (p<0.001). At final follow-up, 27 patients (4.7%) had late adverse events of grade 3 or higher, with liver failure (n=7) and dermatitis (n=7) being most common.ConclusionThis multicenter prospective data registry indicated that PBT for HCC gives good therapeutic effects (3-year local control rate of 90%) with a low risk of severe late adverse events.