Green Tea and Reduction of Breast Cancer Risk

OBJECTIVES: 1. Primary: 1.1 To determine the effects of green tea extract consumption (containing 800 mg EGCG per day) for 12 months on the following recognized biomarkers of breast cancer risk: 1. Mammographic density 2. Circulating concentrations of insulin-like growth factor 1 (IGF-1) and IGF binding protein 3 (IGFBP-3) 3. Circulating concentrations of reproductive hormones (estrone, estradiol, androstenedione) and sex hormone binding globulin (SHBG) 1.2 To determine the effects of COMT genotype on the green tea extract effects described above. 2. Secondary: 2.1 To determine the effects of green tea extract consumption (containing 800 mg EGCG per day) for 12 months on the following hypothesized biomarkers of breast cancer risk: 1. Urinary estrogen metabolites (estrone, estradiol, and their 2-hydroxy, 4-hydroxy, 2-methoxy, and 4-methoxy metabolites, estriol, and 16- hydroxyestrone) 2. Circulating concentrations of F-2 isoprostanes, a recognized biomarker of systemic oxidative stress 2.2 To determine the effects of COMT genotype on the green tea extract effects described above. 2.3 To determine the effects of COMT genotype on catechin metabolism and excretion, as measured by circulating and urinary concentrations.