Flavonoids and survival in stage III colon cancer: CALGB/SWOG 80702 (alliance)

Introduction We sought to evaluate the associations of post-diagnostic consumption of flavonoids and flavonoid-rich foods with survival among patients with stage III colon cancer enrolled in a clinical trial. Methods We conducted a prospective observational study of 1625 patients with stage III colon cancer enrolled in the CALGB/SWOG 80702 (Alliance) randomized adjuvant chemotherapy trial who completed a self-reported food frequency questionnaire within 6 weeks of and again 14-16 months post-randomization. Intakes of flavonoids overall and by subclasses (anthocyanidins, flavanones, flavan-3-ols, flavones, flavonols, isoflavones) were computed by multiplying the consumption frequency of each dietary item by the nutrient content of its respective specified portions. Multivariable analyses for the primary (disease-free survival [DFS]) and secondary (overall survival [OS]) endpoints were adjusted for sociodemographic, clinical, dietary, and lifestyle factors. Bonferroni corrections were applied for analyses of flavonoid subclasses and flavonoid-rich foods. Results Over median follow-up of 5.9 years, flavonoid consumption either overall or by subclasses was not significantly associated with survival outcomes, with a hazard ratio (HR) (95% confidence interval [CI]) of 1.01 (0.75-1.37) for DFS among those in the highest relative to lowest consumption quintiles of total flavonoids. Exploratory analyses of flavonoid-rich foods intake did not demonstrate significant associations with DFS or OS after Bonferroni correction. Conclusion Among resected stage III colon cancer patients who received standardized treatment and follow-up within a nationwide randomized clinical trial, consumption of flavonoids was not associated with survival outcomes. ClinicalTrials.gov identifier: NCT01150045