Meta-analysis of the relationship between preoperative systemic immune inflammation index and prognosis of patients with biliary tract cancer.

Objective

To evaluate the prognostic value of preoperative systemic immune-inflammation index (SII) for overall survival, recurrence-free survival, and clinicopathological features in patients with biliary tract cancer (BTC).

Methods

We systematically searched PubMed, Embase, Web of Science, Cochrane Library, and major Chinese databases. Seventeen studies involving 4,965 patients were included. Study quality was assessed using the Newcastle-Ottawa Scale (NOS). Pooled hazard ratios (HR) or odds ratios (OR) with 95% confidence intervals (CIs) were calculated using random- or fixed-effects models. Subgroup, sensitivity analyses, and funnel plots were conducted to explore heterogeneity and assess robustness.

Results

High preoperative SII was significantly associated with worse overall survival (OS) (HR = 1.98, 95% CI = 1.76-2.23, p < 0.001) and recurrence-free survival (RFS) (HR = 1.57, 95% CI = 1.34-1.84, p < 0.001). It also correlated with a higher risk of lymph node metastasis (OR = 1.97, 95% CI = 1.52-2.55, p < 0.001), but showed no significant associations with vascular invasion, tumor differentiation, or perineural invasion.

Conclusion

Preoperative SII is an effective prognostic predictor for BTC, where elevated levels indicate poorer survival outcomes and increased likelihood of vascular and lymph node involvement.