Blood polyphenol concentrations and differentiated thyroid carcinoma in women from the European Prospective Investigation into Cancer and Nutrition (EPIC) study

Background: Polyphenols are natural compounds with anticarcino-genic properties in cellular and animal models, but epidemiologicalevidence determining the associations of these compounds withthyroid cancer (TC) is lacking.Objectives:The aim of this study was to evaluate the relationsbetween blood concentrations of 36 polyphenols and TC risk in EPIC(the European Prospective Investigation into Cancer and Nutrition).Methods:A nested case–control study was conducted on 273 femalecases (210 papillary, 45 follicular, and 18 not otherwise specifiedTC tumors) and 512 strictly matched controls. Blood polyphenolconcentrations were analyzed by HPLC coupled to tandem MS afterenzymatic hydrolysis. Results:Using multivariable-adjusted conditional logistic regressionmodels, caffeic acid (ORlog2: 0.55; 95% CI: 0.33, 0.93) andits dehydrogenated metabolite, 3,4-dihydroxyphenylpropionic acid(ORlog2: 0.84; 95% CI: 0.71, 0.99), were inversely associated withdifferentiated TC risk. Similar results were observed for papillaryTC, but not for follicular TC. Ferulic acid was also inverselyassociated only with papillary TC (ORlog2: 0.68; 95% CI: 0.51, 0.91).However, none of these relations was significant after Bonferronicorrection for multiple testing. No association was observed for anyof the remaining polyphenols with total differentiated, papillary, orfollicular TC.Conclusions:Blood polyphenol concentrations were mostly notassociated with differentiated TC risk in women, although our study raises the possibility that high blood concentrations of caffeic, 3,4-dihydroxyphenylpropionic, and ferulic acids may be related to alower papillary TC risk.