Complete Response of Hepatocellular Carcinoma With Inferior Vena Cava Tumor Thrombus and Right Atrium Involvement to Combined Radiotherapy and Immunotherapy: A Case Report.

A 66-year-old male with advanced hepatocellular carcinoma, including the portal vein and inferior vena cava tumor thrombi extending to right atrium, received Atezolizumab/Bevacizumab and radiotherapy. In the first 2 weeks, he exhibited fever, elevated C-reactive protein and lactate dehydrogenase levels, and intratumoral bleeding, indicating an antitumor immune response. He achieved a complete response by week 6, maintained until week 89, despite grade 3 pneumonitis and grade 2 proteinuria. This case demonstrates that combining radiotherapy and immunotherapy can be an effective and tolerable treatment for advanced hepatocellular carcinoma with macrovascular invasion, though further studies are needed to confirm the safety and efficacy of this strategy.