• The Ohio State University, Columbus, Ohio, United States.
• The Ohio State University, Columbus, OH, United States.
• The Ohio State University College of Medicine, Columbus, Ohio, United States.

BACKGROUND: Most Colorectal cancers arise from adenomas, and though insulinemic and inflammatory dietary patterns have been associated with colorectal cancer risk, these dietary patterns have not been studied in relation to adenoma risk.

METHODS: Using data from 21,192 participants in the Prostate, Lung, Colorectal, and Ovarian (PLCO) Cancer screening cohort, we calculated the Empirical Dietary Index for Hyperinsulinemia (EDIH), Empirical Dietary Inflammatory Pattern (EDIP) and overall dietary quality measured via the Healthy Eating Index (HEI-2015), from food frequency questionnaires (FFQ). In multivariable-adjusted logistic regression, we investigated associations of these dietary indices with adenoma (any adenoma, advanced adenoma, n=19,493), and recurrent adenoma (n=1,699).

RESULTS: EDIH was not associated with adenoma or advanced adenoma but was marginally associated with recurrent adenoma. The OR (95%CI) comparing highest (lowest insulinemic) versus lowest (most hyperinsulinemic) quintiles was 0.76 (0.55, 1.05) after multivariable adjustment including BMI. EDIP and HEI-2015 were not associated with any of the three outcomes.

CONCLUSIONS: In the PLCO cohort, we did not observe substantial associations between dietary patterns and risk of colorectal adenomas.

IMPACT: Pending confirmation in larger prospective studies, our findings suggest that these dietary patterns may not substantially affect colorectal cancer risk via the adenoma-carcinoma sequence.