Efficacy of Radiotherapy in Combination with Immune Checkpoint Blockade for Hepatocellular Carcinoma and Portal Vein Tumor Thrombosis

Background/Aims: Hepatocellular carcinoma (HCC) with portal vein tumor thrombosis (PVTT) is associated with poor prognosis and low response rates to standard atezolizumab plus bevacizumab therapy (atezo/bev). This study aimed to evaluate the safety and efficacy of radiation therapy (RT) in patients with HCC and PVTT receiving atezo/bev treatment.Methods: This retrospective cohort study included patients with HCC and PVTT treated at a tertiary referral center in Korea. Eligible patients had Child-Pugh class A liver function and an Eastern Cooperative Oncology Group performance status of ≤ 1, and were not candidates for surgical resection or loco-regional therapies. Cox regression analysis was used to identify predictors of progression-free survival (PFS) and overall survival (OS).Results: A total of 85 patients were included, 55 of whom received atezo/bev alone and 30 received atezo/bev combined with RT. There was no significant difference in disease control rate between the two groups (25% vs. 30%, p = 0.65), nor in PFS or OS (median PFS, 143 vs. 289 days, p = 0.17; median OS, 293 vs. 416 days, p = 0.16). However, subgroup analysis, excluding patients with main portal trunk invasion, showed that the addition of RT significantly improved both PFS (adjusted hazard ratio [aHR], 0.29; p = 0.002) and OS (aHR, 0.33; p = 0.01). No clinical or laboratory deteriorations were observed after RT.Conclusions: These findings suggest that the addition of RT to PVTT may be beneficial in patients with preserved liver function without main portal vein involvement.