Purpose: Chronic inflammation has been hypothesized to play a significant role in the aetiology of cancer, including gastric cancer. In the present study, we sought to examine pre-diagnostic systemic cytokine levels in plasma, which can be seen as markers of aggregate inflammation, and risk of distal gastric cancer in a case-control study nested within the prospective Shanghai Men's Health Study.
Methods: Circulating levels of eight inflammation-related cytokines were measured in the plasma collected at baseline for 180 incident cases of distal gastric cancer and 358 matched controls. Helicobacter pylori sero-positivity was assessed using multiplex serology. Conditional logistic regression was used to calculate odds ratios (ORs) and 95 % confidence intervals (CI).
Results: Individuals with IL-8 levels above the lowest quartile were at twofold increased odds of gastric cancer [OR 1.91 (95 % CI 1.05-3.46), OR 2.10 (95 % CI 1.19-3.74), and OR 2.30 (95 % CI 1.26-4.19), for the second through fourth quartiles, respectively]. While there were suggestions of an increase in risk with increased level of many of the other cytokines measured (IL-1β, IL-2, IL-4, IL-6, IL-10, TNF-α, and IFN-γ), no significant associations were found at the p < 0.05 level. Infection with CagA-positive H. pylori did not modify these associations.
Conclusions: In a population with high gastric cancer incidence and high H. pylori prevalence, increased circulating levels of IL-8 may indicate increased risk of gastric cancer. These findings add to our understanding of the disease and further efforts to uncover biomarkers of disease risk.