title: Plasma tea polyphenol levels and subsequent risk of breast cancer among Japanese women: a nested case-control study.
abstract: Although many in vitro and animal studies have suggested a protective effect of green tea against breast cancer, findings from epidemiological studies have been inconsistent. No study has used prediagnostic biomarkers of tea polyphenols, which might play a protective role. A total of 24,226 women aged 40 to 69 years in the Japan Public Health Center-based Prospective Study who responded to the baseline questionnaire and provided blood in 1990-1995 were followed to December 2002. During a mean 10.6 years of follow-up, 144 newly diagnosed breast cancers were identified. Two matched controls for each case were selected from the cohort. Plasma levels of (-)-epigallocatechin (EGC), (-)-epicatechin (EC), (-)-epigallocatechin-3-gallate (EGCG), and (-)-epicatechin-3-gallate (ECG) were measured, and the odds ratio (OR) of breast cancer according to plasma level was estimated using a conditional logistic regression model. We found no statistically significant association between plasma tea polyphenol levels and breast cancer risk. Adjusted ORs for the highest versus lowest group were 0.90 (95% CI 0.42-1.96; P for trend = 0.98) for EGC, 0.95 (95% CI 0.43-2.08; P for trend = 0.86) for EC, 1.21 (95% CI 0.52-2.80; P for trend = 0.53) for EGCG, and 1.75 (95% CI 0.81-3.78; P for trend = 0.15) for ECG. Stratified analyses according to baseline menopausal status showed no remarkable difference between two strata. This nested case-control study found no overall association between plasma tea polyphenols and the risk of breast cancer in Japan.
authors.affiliation: Epidemiology and Prevention Division, Research Center for Cancer Prevention and Screening, National Cancer Center, Chuo-ku, Tokyo, Japan. moiwasak@ncc.go.jp
authors.forename: Motoki
authors.initials: M
authors.lastname: Iwasaki
authors.forename: Manami
authors.initials: M
authors.lastname: Inoue
authors.forename: Shizuka
authors.initials: S
authors.lastname: Sasazuki
authors.forename: Tsutomu
authors.initials: T
authors.lastname: Miura
authors.forename: Norie
authors.initials: N
authors.lastname: Sawada
authors.forename: Taiki
authors.initials: T
authors.lastname: Yamaji
authors.forename: Taichi
authors.initials: T
authors.lastname: Shimazu
authors.forename: Walter C
authors.initials: WC
authors.lastname: Willett
authors.forename: Shoichiro
authors.initials: S
authors.lastname: Tsugane
mesh_terms: D000328:Adult; D000368:Aged; D044466:Asian People / Q000706:statistics & numerical data; D001943:Breast Neoplasms / Q000208:ethnology / Q000209:etiology* / Q000517:prevention & control; D016022:Case-Control Studies; D002392:Catechin / Q000031:analogs & derivatives / Q000097:blood; D005260:Female; D005419:Flavonoids / Q000097:blood*; D006801:Humans; D007564:Japan / Q000453:epidemiology; D016015:Logistic Models; D008875:Middle Aged; D016017:Odds Ratio; D010636:Phenols / Q000097:blood*; D059808:Polyphenols; D011446:Prospective Studies; D018570:Risk Assessment; D012307:Risk Factors; D011795:Surveys and Questionnaires; D013662:Tea; D013997:Time Factors
chemical_list: D005419:Flavonoids; D010636:Phenols; D059808:Polyphenols; D013662:Tea; D002392:Catechin; C062669:epicatechin gallate; C045651:epigallocatechin gallate; C057580:gallocatechol