Prognostic and clinicopathological significance of systemic immune-inflammation index in pancreatic cancer: a meta-analysis of 2,365 patients

The prognostic value of the systemic immune-inflammation index (SII) in patients with pancreatic cancer is conflicting according to previous investigations. Therefore, we performed a meta-analysis to explore the association between SII and pancreatic cancer prognosis. Electronic databases were searched for studies exploring the association of SII with prognostic outcomes in pancreatic cancer. The endpoints were overall survival (OS), disease-free survival (DFS), recurrence-free survival (RFS), progression-free survival (PFS), cancer-specific survival (CSS), and clinicopathological parameters. The prognostic value of SII was estimated by hazard ratio (HR) or odds ratio (OR) with a 95% confidence interval (CI). Nine studies containing 11 cohorts with 2,365 subjects in total were included in this meta-analysis. Elevated SII was associated with poor OS (HR=1.50, 95% CI=1.15–1.96, p=0.002), RFS/PFS/DFS (HR=1.52, 95% CI=1.01–2.28, p=0.045), and CSS (HR=2.60, 95% CI=1.65–4.09, p < 0.001) in patients with pancreatic cancer. Additionally, there was no significant association between SII and other parameters in pancreatic cancer such as sex, tumor location, lymph node metastasis, tumor-node-metastasis stage, vascular invasion, and grade. This meta-analysis suggested that elevated SII was a significant prognostic marker for short-term and long-term survival outcomes in patients with pancreatic cancer.