A patient alive without disease 32 months after conversion surgery following lenvatinib treatment for hepatocellular carcinoma with a tumor thrombus originating in the middle hepatic vein and reaching the right atrium via the suprahepatic vena cava: a case report.

Conversion surgery for initially unresectable hepatocellular carcinoma appears to be increasing in incidence since the advent of new molecular target drugs and immune checkpoint inhibitors; however, reports on long-term outcomes are limited and the prognostic relevance of this treatment strategy remains unclear. Herein, we report the case of a 75-year-old man with hepatocellular carcinoma, 108 mm in diameter, accompanied by a tumor thrombus in the middle hepatic vein that extended to the right atrium via the suprahepatic vena cava. He underwent conversion surgery after preceding lenvatinib treatment and is alive without disease 51 months after the commencement of treatment and 32 months after surgery. Just before conversion surgery, after 19 months of lenvatinib treatment, the main tumor had reduced in size to 72 mm in diameter, the tip of the tumor thrombus had receded back to the suprahepatic vena cava, and the tumor thrombus vascularity was markedly reduced. The operative procedure was an extended left hepatectomy with concomitant middle hepatic vein resection. The tumor thrombus was removed under total vascular exclusion via incision of the root of the middle hepatic vein. Histopathological examination revealed that more than half of the liver tumor and the tumor thrombus were necrotic.