Background: African Americans have a higher risk of developing lung cancer than European Americans. Previous studies suggested that certain circulating cytokines were associated with lung cancer. We hypothesized that variations in serum cytokine levels exist between African Americans and European Americans, and increased circulating cytokine levels contribute to lung cancer differently in the two races.

Methods: Differences in 10 serum cytokine levels, IL1β, IL4, IL5, IL6, IL8, IL10, IL12, granulocyte macrophage colony-stimulating factor, IFNγ, and TNFα, between 170 African-American and 296 European-American controls from the National Cancer Institute-Maryland (NCI-MD) case–control study were assessed. Associations of the serum cytokine levels with lung cancer were analyzed. Statistically significant results were replicated in the prospective Prostate, Lung, Colorectal, and Ovarian Cancer Screening Trial and the Wayne State University Karmanos Cancer Institute case–control study.

Results: Six cytokines, IL4, IL5, IL8, IL10, IFNγ, and TNFα, were significantly higher among European-American as compared with African-American controls. Elevated IL6 and IL8 levels were associated with lung cancer among both races in all three studies. Elevated IL1β, IL10, and TNFα levels were associated with lung cancer only among African Americans. The association between elevated TNFα levels and lung cancer among European Americans was significant after adjustment for additional factors.

Conclusions: Serum cytokine levels vary by race and might contribute to lung cancer differently between African Americans and European Americans.

Impact: Future work examining risk prediction models of lung cancer can measure circulating cytokines to accurately characterize risk within racial groups. Cancer Epidemiol Biomarkers Prev; 25(3); 488–97. ©2015 AACR.