Innate immunity gene polymorphisms and the risk of colorectal neoplasia

Inherited variation in genes that regulate innate immunity and inflammation may contribute to colorectal neoplasia risk. To evaluate this association, we conducted a nested casecontrol study of 451 colorectal cancer cases, 694 colorectal advanced adenoma cases and 696 controls of European descent within the Prostate, Lung, Colorectal and Ovarian Cancer Screening Trial. A total of 935 tag single-nucleotide polymorphisms (SNPs) in 98 genes were evaluated. Logistic regression was used to estimate odds ratios (ORs) and 95% confidence intervals (CIs) for the association with colorectal neoplasia. Sixteen SNPs were associated with colorectal neoplasia risk at P < 0.01, but after adjustment for multiple testing, only rs2838732 (ITGB2) remained suggestively associated with colorectal neoplasia (ORper T allele 0.68, 95% CI: 0.570.83, P 7.7 10(5), adjusted P 0.07). ITGB2 codes for the CD18 protein in the integrin beta chain family. The ITGB2 association was stronger for colorectal cancer (ORper T allele 0.41, 95% CI: 0.300.55, P 2.4 10(9)) than for adenoma (ORper T allele 0.84, 95%CI: 0.691.03, P 0.08), but it did not replicate in the validation study. The ITGB2 rs2838732 association was significantly modified by smoking status (P value for interaction 0.003). Among never and former smokers, it was inversely associated with colorectal neoplasia (ORper T allele 0.5, 95% CI: 0.370.69 and ORper T allele 0.72, 95% CI: 0.540.95, respectively), but no association was seen among current smokers. Other notable findings were observed for SNPs in BPI/LBP and MYD88. Although the results need to be replicated, our findings suggest that genetic variation in inflammation-related genes may be related to the risk of colorectal neoplasia.