The epidemiology of breast cancer risk factors and endogenous sex hormones in postmenopausal women

• Main Author: Chan, M.-F.
• Published: University of Cambridge 2008
• Subjects: 610.21
• Online Access: http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.597420

Reproductive and lifestyle factors are associated with breast cancer risk. More recent prospective studies also report the relationship between endogenous sex hormones and sex hormone-binding globulin (SHBG) and postmenopausal breast cancer risk. The correlates of these endogenous hormones are unclear. This study comprises 2 parts. The main part examines the relationship between endogenous sex hormones and anthropometric, lifestyle and reproductive risk factors for breast cancer among 2,114 postmenopausal women not using hormone replacement therapy in Norfolk, United Kingdom, in the European Prospective Investigation of Cancer (EPIC)-Norfolk Study. The study then explores breast cancer risk factors in 9,986 postmenopausal women in the whole cohort. Women were recruited from general practices in Norfolk. Participants completed a detailed questionnaire on their health and lifestyle and attended health examination at designated clinics where clinical and anthropometric measures were taken and non-fasting blood samples collected. Estrogens (estradiol, estrone), androgens (testosterone, androstenedione), 17α-hydroxyprogesterone and SHBG were measured. Age, anthropometry, and lifestyle and reproductive factors including indices of general obesity and central obesity, use of exogenous hormones (oral contraceptives and hormone replacement therapy), physical activity, smoking status, ages at menarche, first birth and menopause, parity and a past history of ovariectomy were associated with circulating hormone and SHBG concentrations. Effects on endogenous sex hormones may be plausible mechanisms through which these factors may influence breast cancer risk. In the prospective analysis, increasing height and a greater change in body mass index between age 20 and the study baseline were associated with increased risk of incident cases of postmenopausal breast cancer.