Although control of the host cytokine network is known to influence gastric cancer susceptibility, the specific inflammatory responses in gastric carcinogenesis remain unclear. We prospectively examined the relationships between gastric cancer risk and plasma levels of interleukin (IL)-1β, IL-6, IL-8 and tumor necrosis factor (TNF)-α in a nested case control study within The Shanghai Women's Health Study. Two controls were matched to each case on the basis of age, menopausal status, and sample collection parameters. The associations between gastric cancer risk and tertiles of cytokine levels were estimated by odds ratios (OR) and 95% confidence intervals (CI) from conditional logistic regression, adjusting for education. During a median follow-up period of 4 years (range 0.1-8 years), 141 women developed gastric cancer and were matched to 282 cancer-free study participants. Elevated levels of plasma IL-6 were associated with an increased risk of gastric cancer (P(trend) = 0.04). Risk increased 70% (OR = 1.7; 95% CI 1.0, 3.0) for women in the highest tertile (>4 pg/mL) of IL-6 compared with those in the lowest tertile (<1.8 pg/mL). The association between gastric cancer risk and IL-6 was stronger after 4 years of follow-up (OR = 2.6 [95% CI 1.0, 6.7] for highest versus lowest tertile) compared with an OR of 1.4 (95% CI 0.7, 2.9) for those diagnosed within 1-4 years of follow-up. No associations were observed with the other pro-inflammatory cytokines examined, namely IL-1β, IL-8, and TNF-α. Systemic plasma IL-6 levels may inform long-term gastric cancer risk. This novel finding awaits confirmation in future studies with sequential plasma collection.
© 2011 Japanese Cancer Association and this article is a US Government work and is in the public domain in the USA.