Systemic immune-inflammation index predicts survival in gastric cancer: a systematic review and meta-analysis

Objective To comprehensively assess the association of pretreatment systemic immune-inflammation index (SII) with the prognosis of gastric cancer patients. Methods PubMed, Web of Science, Embase, and the Cochrane Library were searched to select studies exploring the association of SII with the overall survival (OS), progression-free survival (PFS) or recurrence-free survival (RFS) of gastric cancer. We pooled the hazard ratios (HRs) with 95% confidence intervals (CIs) using a random-effects model. Robustness was assessed by sensitivity analyses, and publication bias was evaluated using funnel plots and Egger’s regression test. Results A total of 61 studies involving 66 cohorts and 31,608 patients were included in this meta-analysis, with most studies adopting a retrospective design and only one prospective study enrolled. Elevated pretreatment SII was significantly correlated with inferior OS (HR = 1.48, 95% CI: 1.36–1.62), PFS (HR = 1.43, 95% CI: 1.30–1.58), and RFS (HR = 1.38, 95% CI: 1.09–1.76). Subgroup analyses demonstrated that the magnitude of the prognostic association varied across treatment modalities and geographic regions. Conclusion In conclusion, we found that elevated pretreatment SII is a potential biomarker for adverse prognosis in gastric cancer patients. However, since nearly all included studies were retrospective and only one was a prospective study, our findings support the prognostic value of SII, but prospective validation is required before routine clinical implementation. Systematic review registration https://www.crd.york.ac.uk/PROSPERO/ , identifier CRD420261321880.