(LB03-02-26) Dietary Quality and Early Colorectal Cancer Markers: A Cross-Sectional Exploration of Polyp Subphenotypes and Mucosal Biofilm

Objectives: Colorectal cancer (CRC) incidence is rising among adults under 50, yet dietary research largely focuses on CRC incidence rather than preclinical markers. While the Alternative Healthy Eating Index (AHEI) inversely correlates with conventional polyps, links to broader colon polyp (CP) phenotypes and mucosal biofilm (MB) formation are understudied. This study preliminarily explored these associations.

Methods: This cross-sectional analysis used data from a dietary substudy nested within the Johns Hopkins Biofilm Colonoscopy Study. Dietary quality was assessed using the AHEI, derived from post-colonoscopy Block Food Frequency Questionnaire. CP subphenotype (no polyps, adenomatous (AP), sessile serrated (SSP)/synchronous) and MB formation, yes/no, were examined as outcomes. AHEI functional form–tertile, continuous, literature-based cut point at 65, restricted cubic spline–was selected via information criterion comparison (AIC/BIC). Multinomial and binary logistic regression were used for CP and MB, respectively, across unadjusted, age-adjusted, and multivariable-adjusted models. Significance was set at p < 0.05 with FDR correction.

Results: Of 227 participants (mean age 65.2 years, predominantly White females), 33.1% had no polyps, 36.6% had AP, 30.4% had SSP/synchronous polyps, and 6.2% had MB. No significant associations between AHEI and either outcome were observed across all model specifications. The spline curve suggested a non-linear U-shaped trend for AP and SSP/synchronous, with lowest polyp probability at mid-range AHEI (~48–50). Higher AHEI scores were non-significantly associated with lower MB odds (multivariable OR=0.41, 95% CI: 0.06–1.70, p=0.28). Age (OR=1.07/year, 95% CI= 1.02–1.11, p=0.003) and obesity (OR=2.57, 95% CI=1.17–5.06, p=0.016) were independently associated with AP in the tertile model.

Conclusions: These preliminary findings suggest that dietary quality may relate to early CRC markers through complex, subphenotype-specific pathways rather than a uniform linear gradient. The directional biofilm signal is consistent with biological evidence linking dietary quality to mucosal barrier integrity. Future studies with larger, sex-stratified samples and dietary indices sensitive to gut microbiome modulation are warranted to clarify these relationships.

Funding Sources: NIH grant R01CA196845