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: Motoki Iwasaki, Manami Inoue, Shizuka Sasazuki, Tsutomu Miura, Norie Sawada, Taiki Yamaji, Taichi Shimazu, Walter C Willett, Shoichiro Tsugane
• Journal: Breast cancer research and treatment (Breast Cancer Res Treat) Vol. 124 Issue 3 Pg. 827-34 (Dec 2010) ISSN: 1573-7217 [Electronic] Netherlands
• PMID: 20440552 (Publication Type: Journal Article, Research Support, Non-U.S. Gov't)

Chemical References

• Flavonoids
• Phenols
• Polyphenols
• Tea
• Catechin
• epicatechin gallate
• epigallocatechin gallate
• gallocatechol

Topics

• Adult
• Aged
• Asian People (statistics & numerical data)
• Breast Neoplasms (ethnology, etiology, prevention & control)
• Case-Control Studies
• Catechin (analogs & derivatives, blood)
• Female
• Flavonoids (blood)
• Humans
• Japan (epidemiology)
• Logistic Models
• Middle Aged
• Odds Ratio
• Phenols (blood)
• Polyphenols
• Prospective Studies
• Risk Assessment
• Risk Factors
• Surveys and Questionnaires
• Tea
• Time Factors