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Flavonoids have been shown to inhibit colon cancer cell proliferation in vitro and protect against colorectal carcinogenesis in animal models. However, epidemiological evidence on the potential role of flavonoid intake in colorectal cancer (CRC) development remains sparse and inconsistent. We evaluated the association between dietary intakes of total flavonoids and their subclasses and risk of development of CRC, within the European Prospective Investigation into Cancer and Nutrition (EPIC) study. A cohort of 477,312 adult men and women were recruited in 10 European countries. At baseline, dietary intakes of total flavonoids and individual subclasses were estimated using centre-specific validated dietary questionnaires and composition data from the Phenol-Explorer database. During an average of 11 years of follow-up, 4,517 new cases of primary CRC were identified, of which 2,869 were colon (proximal = 1,298 and distal = 1,266) and 1,648 rectal tumours. No association was found between total flavonoid intake and the risk of overall CRC (HR for comparison of extreme quintiles 1.05, 95% CI 0.93-1.18; p-trend = 0.58) or any CRC subtype. No association was also observed with any intake of individual flavonoid subclasses. Similar results were observed for flavonoid intake expressed as glycosides or aglycone equivalents. Intake of total flavonoids and flavonoid subclasses, as estimated from dietary questionnaires, did not show any association with risk of CRC development., (© 2016 UIC.)

The aim was to investigate the association between pre-diagnostic intakes of polyphenol classes (flavonoids, lignans, phenolic acids, stilbenes, and other polyphenols) in relation to breast cancer survival (all-cause and breast cancer-specific mortality). We used data from the European Prospective Investigation into Cancer and Nutrition cohort. Pre-diagnostic usual diet was assessed using dietary questionnaires, and polyphenol intakes were estimated using the Phenol-Explorer database. We followed 11,782 breast cancer cases from time of diagnosis until death, end of follow-up or last day of contact. During a median of 6 years, 1482 women died (753 of breast cancer). We related polyphenol intake to all-cause and breast cancer-specific mortality using Cox proportional hazard models with time since diagnosis as underlying time and strata for age and country. Among postmenopausal women, an intake of lignans in the highest versus lowest quartile was related to a 28 % lower risk of dying from breast (adjusted model: HR, quartile 4 vs. quartile 1, 0.72, 95 % CI 0.53; 0.98). In contrast, in premenopausal women, a positive association between lignan intake and all-cause mortality was found (adjusted model: HR, quartile 4 vs. quartile 1, 1.63, 95 % CI 1.03; 2.57). We found no association for other polyphenol classes. Intake of lignans before breast cancer diagnosis may be related to improved survival among postmenopausal women, but may on the contrary worsen the survival for premenopausal women. This suggests that the role of phytoestrogens in breast cancer survival is complex and may be dependent of menopausal status.