Abstract
Previous studies that explored the prognostic and clinical value of the systemic immune-inflammation index (SII) in biliary tract cancer (BTC) had inconsistent results. We conducted this meta-analysis to evaluate the prognostic and clinicopathological role of the SII in biliary tract cancer. Combined analysis demonstrated that high SII levels had worse overall survival (HR = 1.92, 95% CI: 1.66-2.21, p < 0.001) than those with low SII levels. And an elevated SII was associated with lymph node metastasis (OR = 1.44, 95% CI = 1.18-1.76; p < 0.001), TNM stage (OR = 1.49, 95% CI = 1.05-2.13; p = 0.028), and vascular invasion (OR = 1.49, 95% CI = 1.05-2.13; p = 0.028). Conversely, no significant association between a high SII and sex or tumor differentiation was found. Our findings demonstrate that high SII levels were correlated with unfavorable survival outcomes among patients with BTC and that they were also correlated with some higher malignancy features of BTC.