Systemic Immune-Inflammation Index (SII) is Useful to Predict Survival Outcomes in Patients After Liver Transplantation for Hepatocellular Carcinoma within Hangzhou Criteria

Background: There is growing evidence that the systemic immune-inflammation index (SII), a novel prognostic biomarker based on peripheral lymphocyte, neutrophil, and platelet counts, is associated with poor prognosis for several tumors. However, the prognostic value of SII in patients with hepatocellular carcinoma (HCC) who undergo liver transplantation (LT) remains unclear. The aim of this study was to determine the correlation between SII and prognosis in these patients. Methods: This retrospective study involved 150 patients with HCC who underwent LT within the Hangzhou criteria. The optimal cut-off value was determined by receiver-operating characteristic (ROC) curve analysis to stratify the patients into those with a high SII and those with low SII. The Kaplan-Meier method and the Cox proportional hazards model were used to evaluate the prognostic value of SII. Finally, we calculated the area under the ROC curve to compare the prognostic power of SII, platelet-to-lymphocyte ratio (PLR), neutrophil-to-lymphocyte ratio (NLR), and monocyte-to-lymphocyte ratio (MLR). Results: Patients were divided into high SII (≥ 226) and low SII (< 226) groups. Five-year overall survival (OS) was lower in the high SII group than in the low SII group (56.1% vs. 82.4%, p = 0.002). SII ≥ 226 × 109/L, maximum tumor size> 5 cm, microvascular invasion, and poor differentiation were independent prognostic factors for OS. However, SII did not predict 5-year recurrence-free survival (high vs. low SII: 64.1% vs. 78.4%, p = 0.073). The area under the ROC curve was greater for SII than for PLR, NLR, and MLR. Conclusions: Preoperative SII may be a powerful prognostic biomarker in patients with HCC who undergo LT within the Hangzhou criteria. SII is superior to PLR, NLR, and MLR for prediction of OS in these patients.