A proinflammatory diet may increase the risk of colorectal cancer, but its role may differ according to individuals' genetic variants. We aimed to examine whether a specific dietary pattern reflecting inflammation was associated with a risk of colorectal cancer and whether IL-17F genetic variant altered this association. In a study of 695 colorectal cancer cases and 1846 controls, we derived a reduced rank regression dietary pattern using 32 food groups as predictors and the plasma C-reactive protein (CRP) concentration as the response. High CRP levels were associated with a high risk of colorectal cancer (OR (95% CI) = 3.58 (2.65⁻4.82) for the highest quartile vs. lowest quartile). After adjusting for potential confounding factors, high pattern scores were associated with a high risk of colorectal cancer (OR (95% CI) = 9.98 (6.81⁻14.62) for the highest quartile vs. lowest quartile). When stratified by the IL-17F rs763780 genotype, this association was stronger for individuals carrying the C allele (p for interaction = 0.034), particularly for individuals with rectal cancer (p for interaction = 0.011). In conclusion, a dietary pattern reflecting inflammation was significantly associated with colorectal cancer risk. Moreover, this association could be modified according to the IL-17F rs763780 genotype and anatomic site.
Keywords: C-reactive protein; IL-17F polymorphism; colorectal cancer; dietary pattern; inflammation.