Inflammatory Cytokines and Lung Cancer Risk in 3 Prospective Studies

To further investigate the role of inflammation in lung carcinogenesis, we evaluated associations between proinflammatory cytokines and lung cancer risk. We conducted a case-control study nested within 3 prospective cohort studies-the Melbourne Collaborative Cohort Study (1990-1994), the Malm Diet and Cancer Study (1991-1996), and the Northern Sweden Health and Disease Study (initiated in 1985)-involving 807 incident lung cancer cases and 807 smoking-matched controls. Conditional logistic regression models adjusting for serum cotinine concentrations were used to estimate odds ratios for lung cancer risk associated with concentrations of interleukin (IL)-1 beta, IL-2, IL-6, IL-8, IL-10, IL-12, interferon., tumor necrosis factor a, and granulocyte-macrophage colony-stimulating factor. We observed a higher lung cancer risk for participants with elevated concentrations of IL-6 and IL-8. These associations seemed to be stronger among former smokers (for fourth quartile vs. first quartile, odds ratio (OR) = 2.70, 95% confidence interval (CI): 1.55, 4.70) and current smokers (OR = 1.99, 95% CI: 1.15, 3.44) for IL-6 and among former smokers (OR = 2.83, 95% CI: 1.18, 6.75) and current smokers (OR = 1.30, 95% CI: 0.69, 2.44) for IL-8. No notable associations were observed among never smokers. Risk associations with IL-6 and IL-8 were observed for blood samples taken close to diagnosis (< 5 years) as well as more than 15 years postdiagnosis.