Serum adiponectin, leptin, C-peptide, homocysteine, and colorectal adenoma recurrence in the polyp prevention trial

Background: Serum adiponectin, leptin, C-peptide, and homocysteine are indicators for obesity, hyperinsulinemia, and chronic inflammation, which have all been associated with colorectal cancer. Aims: To determine whether serum adiponectin, leptin, C-peptide, and homocysteine are associated with fat, fiber, fruit and vegetable, flavonol, or dry bean intake and colorectal adenoma recurrence. Methods: Using logistic regression, we estimated odds ratios (OR) and 95% confidence intervals (95% CI) for adenoma recurrence in 627 participants from the control arm of the Polyp Prevention Trial, a 4-year trial that examined the effectiveness of a low-fat, high-fiber, high-fruit and vegetable diet on adenoma recurrence. Results: Serum concentrations of C-peptide and homocysteine were inversely related to fiber, fruit and vegetable, and flavonol intake and positively related to percentage of calories from fat (all P _trend ≤0.01). High homocysteine concentrations were associated with any (4th versus 1st quartile: OR, 2.26; 95% CI, 1.30-3.94) and more than one adenoma recurrence (OR, 2.11; 95% CI, 1.01-4.40). Individuals in the highest, versus lowest, tertile of serum leptin concentration had a decreased risk of advanced adenoma recurrence (OR, 0.22; 95% CI, 0.06-0.79). Conclusion: Our results suggest that serum homocysteine may serve as an indicator of dietary exposure, including a low-fat and high-fiber, high-fruit and vegetable, and high-flavonol diet, as well as colorectal adenoma recurrence. Impact: Discovering biomarkers that are both modifiable and can predict cancer risk is critical. We identified serum homocysteine as a novel indicator that is modified by diet and predicts risk of adenoma recurrence.