ASPO Abstracts

The role of adiposity, inflammation and insulin response biomarkers in mediating the association between empirical (hypothesis-oriented) dietary patterns and colorectal cancer risk

Authors: Tabung FK, Tchetgen ET, Liu L, Fung TT, Smith-Warner SA, Giovannucci EL

Category: Inflammation & Cancer, Early Detection & Risk Prediction
Conference Year: 2018

Abstract Body:
Background: Adiposity, circulating inflammatory and insulin response biomarkers have been associated with colorectal cancer risk. Dietary patterns including the empirical dietary inflammatory pattern (EDIP) score, developed based on some of these biomarkers, and the Western dietary pattern have been associated with colorectal cancer risk. However, the biological mechanisms underlying these associations have not been formally quantified. We evaluated the extent to which these associations are mediated by body mass index (BMI), circulating inflammatory [C-reactive protein (CRP), interleukin-6 (IL6), TNF-alpha receptor 2, adiponectin, macrophage inhibitory cytokine-1, MIC1)] and insulin response (C-peptide) biomarkers. Methods: We used dietary and biomarker data from 1730 men and women in case-control studies nested within the Nurses’ Health Study and Health Professionals Follow-up Study. We fitted logistic regression models in causal mediation analyses using inverse odds weights, to calculate odds ratios for direct and indirect dietary patterns’ effects on colorectal cancer risk, comparing extreme dietary patterns tertiles (n=1153). We also estimated the proportion of association mediated. Results: Total effects [OR (95%CI)] for participants in the highest tertile were: 1.25 (0.95, 1.63) for EDIP score and 1.30 (0.99, 1.70) for Western pattern score. The proportion (%) of the association mediated was: BMI, 10.5; C-peptide, 15.3; CRP, 15.3; IL6, 17.2; TNFR2, 21.2; MIC1, 14.5, for the EDIP score; and BMI, 6.6; C-peptide 4.4; CRP, 13.5; IL6, 15.8; TNFR2, 9.6; MIC1, 8.4 for the Western pattern score. Conclusion: Our results suggest that, in intervention studies, adiposity, circulating inflammatory and insulin response biomarkers may be monitored as intermediates partially linking dietary intake to colorectal cancer development.

Keywords: mediation, inverse odds weights, dietary patterns, colorectal cancer