Abstract Background and aims Hepatocellular carcinoma (HCC) with portal vein tumor thrombus (PVTT) has an extremely poor prognosis. A previous study proved that low-dose radiotherapy (RT) could prolong the prognosis of HCC patients with PVTT. This study aims to explore the sensitivity of PVTT to RT treatment. Methods Patients were selected based on imaging diagnosis of HCC accompanied by PVTT and received combined treatment of radiotherapy, antiangiogenic drugs and immune checkpoint inhibitors, followed by hepatectomy or liver transplantation from January 2019 to August 2022. The efficacy was evaluated by Response Evaluation Criteria in Solid Tumors (RECIST) guidelines and pathological assessment. The sensitivity of tumor cells to the treatment was compared between the primary tumor (PT)and PVTT by analyzing their residual tumor and pathologic complete remission (PCR) incidence. Results Data from 14 patients were collected in the study. After combined treatment, the size of PVTT decreased more significantly than that of the primary tumor in the imaging study (p < 0.05). The residual cancer was significantly more restrictive than that of primary tumor in paired patients based on pathological measurement (p = 0.008). The PCR incidence of the primary tumor (21.42%) was significantly lower (p = 0.008) than that of PVTT in the pathologic study (78.57%). Conclusion PVTT is more sensitive to radiotherapy treatment than the primary tumor in patients with HCC. This combination therapy might be an effective option as a downstaging therapy for patients with HCC with PVTT.
