Objectives: Tumor-infiltrating inflammatory cells (TIICs) in pancreatic ductal adenocarcinoma (PDAC) are reported to initiate and exacerbate invasion and metastasis. Interleukin-8 (IL-8), a proinflammatory cytokine, is expressed in both neoplastic cells and TIICs in PDAC tissues and increased in patient serum. The aim of this study is to evaluate the values of IL-8 expression profiles in tumor tissues and predict the source of serum IL-8 in PDAC patients.
Methods: We used 2 independent groups of PDAC patient samples that included 240 cases. Tissue expression profiles of cytokines were evaluated with immunohistochemistry and serum levels with human IL-8 assay. The prognostic values of the variables were assessed by Kaplan-Meier or Cox regression analysis.
Results: Higher levels of IL-8-positive TIICs but not tumor cells in PDAC patients correlated with worse prognosis (P = 0.009) and higher blood serum IL-8 levels (P = 0.002). Controlling other independent factors, the relative hazard ratio for PDAC with higher IL-8-positive TIIC levels compared with those with lower TIIC levels was 1.588 (95% confidence interval, 1.04-2.42).
Conclusions: Higher IL-8-positive TIIC levels in PDAC tumors indicate poorer prognosis and positively correlate with serum IL-8 concentrations and vice versa. These data suggested that IL-8 might have a potential target for PDAC therapies.