Systemic immune-inflammation index and the survival of hepatocellular carcinoma patients after transarterial chemoembolization: a meta-analysis

The systemic immune-inflammation index (SII), derived from neutrophil, platelet, and lymphocyte counts, has been associated with prognosis of patients with cancer. We performed a meta-analysis to evaluate the association between pretreatment SII and survival of patients with hepatocellular carcinoma (HCC) after transarterial chemoembolization (TACE). Cohort studies were identified by search of PubMed, Embase, Web of Science, CNKI, and Wanfang databases. Pooling the results was achieved with a random-effect model that incorporates potential heterogeneity between studies. Nine studies including 3557 patients with HCC contributed to the meta-analysis. Compared to patients with a lower SII, HCC patients with a higher pretreatment SII had poor overall survival (OS, hazard ratio [HR] 1.66, 95% confidence interval [CI] 1.25-2.21, p < 0.001; I² = 80%) and poor progression-free survival (PFS, HR 1.28, 95% CI 1.05-1.56, p = 0.01; I² = 0%) after TACE treatment. Further subgroup analyses confirmed a significant association between a high pretreatment SII and poor OS after TACE, which was not significantly affected by study country, sample size, age of the patients, cutoff values for SII, and adjustment of Child-Pugh score or alpha fetoprotein (p for subgroup effect all < 0.05). However, a higher SII was associated with poor OS in studies with follow-up duration ≤ 24 months (HR 1.94, 95% CI 1.39-2.72, p < 0.001), but the association was not statistically significant in studies with follow-up duration > 24 months (HR 1.27, 95% CI: 0.96-1.68, p = 0.09). A higher pretreatment SII was correlated with poor survival of HCC patients after TACE. A preliminary measurement of SII may be valuable for the prediction of the prognosis in HCC patients after TACE.