Repeated Carbon-Ion Radiation Therapy for Intrahepatic Recurrent Hepatocellular Carcinoma.

PURPOSE:This retrospective study aimed to evaluate the safety and efficacy of repeated carbon-ion radiation therapy (CIRT) in patients with intrahepatic recurrent hepatocellular carcinoma (HCC). METHODS AND MATERIALS:We reviewed patients who underwent repeated CIRT for intrahepatic recurrent HCC between 2010 and 2020. RESULTS:Forty-one patients received multiple CIRT courses for HCC. During the second course, 17 (41.5%) and 24 (58.5%) of 41 patients underwent CIRT for local recurrence (LR) and intrahepatic recurrence after the first irradiation, respectively. The median age at the first course was 76 years, and the median tumor size in all the courses was 25 mm. Throughout all CIRT courses, the prescribed dose was 52.8 to 60.0 Gy (relative biological effectiveness), which was delivered in 4 to 12 fractions. The median follow-up period after the first and second CIRT was 40 and 21 months. Median overall survival (OS) after the first and second CIRT were 80 and 27 months, respectively. The 2- and 5-year OS after the first CIRT were 87.8% and 50.1%, and the 2-year OS rate after the second CIRT was 56.0%. The 1- and 2-year local control (LC) after the second CIRT was 93.4% and 83.0%, respectively. The median progression-free survival (PFS) after the second CIRT was 11 months. There were no significant differences in the LC and PFS between patients with LR and out-of-field recurrence (P = .83; 0.28, respectively). The albumin-bilirubin scores at 3 and 6 months after the second CIRT were not significantly different from those before irradiation. According to the Common Terminology Criteria for Adverse Events version 4.0, grade 4 or greater toxicities were not observed. CONCLUSIONS:Repeated CIRT for intrahepatic recurrent HCC was safe and effective, including reirradiation for LR. OS, LC, and PFS were satisfactory, and liver function was preserved. Repeated CIRT could be considered a treatment option for intrahepatic recurrent HCC.