Abstract
Background: The systemic immune-inflammation index (SII) has been found to predict outcomes in many tumors. The purpose of this study was to determine the prognostic value of SII in biliary tract cancer.Methods: We searched PubMed, EMBASE, Web of Science, Cochrane Library, CNKI, CBM, Wanfang and VIP databases from its inception until May 18, 2020. Pooled hazard ratio and 95% confidence interval were calculated to assess the prognostic role of SII in patients with BTC. The main outcomes included the overall survival, cancer-specific survival, disease-free survival and recurrence-free survival. Stata 12.0 was used for statistical analysis.Results: A total of 8 studies involving 2249 patients were eventually included. The results showed that elevated SII was significantly associated with poorer OS (HR=1.56, 95% CI: 1.23–1.99, P<0.001, I2 = 68.1%), poorer DFS/RFS (HR=1.42, 95%CI:1.09–1.84, P =0.009) and poorer CSS (HR =1.55, 95% CI: 1.09–2.21, P<0.014). Subgroup analysis further verified the above results. Conclusions: Higher SII is a predictor of poor prognosis in BTC patients. SII can serve as a useful prognostic indicator and help to evaluate the prognosis and formulate treatment strategies.Registered in PROSPERO: CRD42020184556