BackgroundHepatocellular carcinoma (HCC) ranks third in cancer‐related deaths globally. Despite treatment advances, high post‐hepatectomy recurrence rates (RR), especially with liver fibrosis and hepatitis C virus infection, remain challenging. Key prognostic factors include vascular invasion and perioperative blood loss, impacting extrahepatic recurrence. Natural killer (NK) cells are crucial in countering circulating tumor cells through TRAIL‐mediated pathways. The aim of this study was to validate the liver immune status index (LISI) as a predictive tool for liver NK cell antitumor efficiency, particularly in HCC patients with vascular invasion.MethodsA retrospective analysis of 1337 primary HCC hepatectomies was conducted by the Hiroshima Surgical Study Group of Clinical Oncology (HiSCO). Clinicodemographic data were extracted from electronic medical records. Prognostic indices (FIB‐4, ALBI, ALICE, GNRI, APRI, and LISI) were evaluated using area under the receiver operating characteristic curve values. Survival analyses employed Kaplan–Meier estimations and log‐rank tests.ResultsLISI significantly correlated with other prognostic markers and stratified patients into risk groups with distinct overall survival (OS) and RR. It showed superior predictive performance for 2‐year OS and RR, especially in patients with vascular invasion. Over longer periods, APRI and FIB‐4 index reliabilities improved. The HISCO‐HCC score, combining LISI, tumor burden score, and alpha‐fetoprotein levels, enhanced prognostic accuracy.ConclusionLISI outperformed existing models, particularly in HCC with vascular invasion. The HISCO‐HCC score offers improved prognostic precision, guiding immunotherapeutic strategies and individualized patient care in HCC.