BackgroundThe cachexia index (CXI), which consists of skeletal muscle, inflammation, and nutritional status, has been associated with prognosis in patients with hepatocellular carcinoma (HCC). We hypothesized that dynamic changes in CXI might be associated with long‐term outcomes in HCC.MethodsThis study comprised 131 patients who had undergone primary hepatic resection for HCC between 2008 and 2019. Preoperative CXI (pre‐CXI) and postoperative CXI (post‐CXI) were calculated by the following formula: skeletal muscle index x serum albumin level / neutrophil‐to‐lymphocyte ratio. Pre‐ and post‐CXI were classified into two groups (high vs. low). We retrospectively investigated the association of perioperative dynamic changes in CXI with disease‐free and overall survival.ResultsIn multivariate analyses, negative HBs‐antigen (p = 0.02), high serum PIVKA‐II level (p < 0.01), poor tumor differentiation (p = 0.02), multiple tumors (p < 0.01), microvascular invasion (p < 0.01), partial resection (p < 0.01), postoperative complications (p < 0.01), and low‐pre‐CXI (p < 0.01) were significant predictors of disease‐free survival, while high ICGR15 (p = 0.01), poor tumor differentiation (p < 0.01), multiple tumors (p = 0.01), postoperative complications (p < 0.01), low‐pre‐CXI (p < 0.01), and low‐post‐CXI (p < 0.01) were significant predictors of overall survival. Low‐post‐CXI was associated with older age (p = 0.045), larger tumor (p < 0.01), longer operation time (p = 0.047), greater intraoperative bleeding (p < 0.01), and intraoperative blood transfusion (p < 0.01). Moreover, dynamic changes in CXI were associated with overall survival in each subgroup of patients with low‐pre‐CXI (p = 0.02) or high‐pre‐CXI (p = 0.03).ConclusionsNot only post‐CXI but also dynamic changes in CXI from pre‐ to post‐hepatectomy can be a prognostic indicator of HCC, providing a compelling rationale for aggressive perioperative nutritional and physical interventions to improve long‐term outcomes.