Plasma lipopolysaccharide-binding protein and colorectal cancer risk: a nested case-control study in the Multiethnic Cohort.

BACKGROUND: Lipopolysaccharide (LPS), an endotoxin found on the outer cell wall of Gram-negative bacteria, increases inflammatory response signaling and may play a role in the pathogenesis of several adverse outcomes, including inflammatory bowel diseases, cardiovascular disease, and cancer. While LPS is hypothesized to be associated with colorectal carcinogenesis, there are relatively few human studies which have examined this association.

METHODS: We examined the association between colorectal cancer (CRC) and plasma lipopolysaccharide-binding protein (LBP), a marker of LPS, in 1,638 participants (819 CRC cases and 819 controls) matched on multiple factors, including age, sex, and race/ethnicity, from the Multiethnic Cohort study. Conditional logistic regression models were used to estimate the multivariable-adjusted odds ratios (OR) and 95% confidence intervals (95% CI).

RESULTS: Compared to individuals whose LBP concentrations were in the lowest quartile, the ORs associated with second, third, and fourth quartiles were 1.23 (95% CI 0.91-1.67), 1.36 (95% CI 1.01-1.83), and 1.01 (95% CI 0.73-1.39), respectively, (p trend  = 0.66). No differences were observed by BMI, fiber intake, saturated fat intake, cancer site, or cancer stage.

CONCLUSIONS: This study did not find an overall statistically significant association between LBP (as a marker of LPS exposure) and CRC. Further prospective studies with multiple LBP measurements are needed to validate current findings.