Prognostic significance of pretreatment systemic immune-inflammation index (SII) in patients with cervical cancer: a meta-analysis

The pretreatment systemic immune-inflammation index (SII) has been previously investigated for its potential in predicting the prognostic outcomes of cervical cancer (CC), but findings remain inconsistent. This meta-analysis aimed to clarify the prognostic value of SII in patients with CC. Web of Science, PubMed, the Cochrane Library, and Embase databases were systematically searched up to October 15, 2025. The prognostic performance of SII in CC was evaluated by calculating pooled hazard ratios (HRs) and 95% confidence intervals (CIs). The primary outcome was overall survival (OS), and the secondary outcome was progression-free survival (PFS). Sixteen studies with a total of 2,840 patients were included. Fifteen studies comprising 2,735 cases were analyzed for OS, and nine studies including 1,349 patients were analyzed for PFS. Elevated SII was significantly associated with poorer OS (HR = 2.13, 95% CI = 1.60–2.85, p < 0.001) and PFS (HR = 1.81, 95% CI = 1.26–2.60, p < 0.001). Sensitivity analysis indicated stable results, confirming the robustness and reliability of the findings for both OS and PFS. No significant publication bias was detected according to Begg’s test. Elevated pretreatment SII is significantly associated with poorer OS and reduced PFS in patients with CC. SII may serve as a reliable and efficient prognostic biomarker for CC.