Background:In vitro studies found that the flavanol epigallocatechin (EGC) and flavonols, but not the flavanol epicatechin (EC), activated glutathione s-transferases (GST), a family of phase II enzymes which detoxify reactive oxygen species, such as catechol estrogen metabolites. Objective: To investigate whether urinary excretion of tea polyphenols interacted with GST polymorphism in relation to breast cancer risk.

Design: We conducted a study of 353 incident breast cancer cases and 701 individually-matched controls nested within the Shanghai Women's Health Study cohort of women aged 40-70 years at baseline. Liquid chromatography tandem mass spectrometry was used to measure urinary excretion of flavanols and flavonols. Real-time multiplex PCR were used to quantify the copy number variation for the GSTM1 and GSTT1 genes.

Results: Urinary excretion of flavonols and flavanols, particularly, EGC(p=0.02), were significantly higher among those null for GSTM1 than those positive for GSTM1. Furthermore, urinary excretion of flavanol EGC significantly interacted with GSTM1 polymorphism (p=0.04), while flavonols, particularly kaempferol, may interact with both GSTM1 and GSTT1 genotype in relation to breast cancer. As a result, flavanols (primarily EGC) and flavonols significantly interacted with the joint genotypes of GSTM1 and GSTT1 in relation to breast cancer risk. Flavonols and flavanols (EGC in particular) were associated with a reduced risk of breast cancer among those null for GSTM1 and GSTT1, whereas flavonols, particularly kaempferol, were significantly associated with an increased risk of breast cancer for those possessing both GSTM1 and GSTT1.

Conclusion: These results, if confirmed, may provide a new avenue for the personalized prevention of breast cancer.

Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 101st Annual Meeting of the American Association for Cancer Research; 2010 Apr 17-21; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2010;70(8 Suppl):Abstract nr LB-412.