A principal component of the Breast Cancer and the Environment Research Centers (BCERCs) are the conduct of prospective epidemiologic studies investigating predictors of early puberty, including breast development, in young girls. While there is substantial uncertainty regarding the causes of early puberty, it is known that there are racial differences, and that overweight and obesity predispose to earlier pubertal onset. Dietary factors are of interest as they may be a source of exogenous estrogens (e.g., phytoestrogens), and they may influence sex hormone metabolism and adiposity. In the BCERC epidemiologic studies, over 1,200 girls aged 6-8 years at baseline were enrolled in centers at three sites: the San Francisco Bay Area, Cincinnati, and New York City. Enrollment into these studies occurred from 2004 through 2007, and girls continue to be followed with annual or semi-annual contacts. Pubertal status is determined through clinical exams assessing Tanner stage for breast or pubic hair development. Among other factors, dietary data was collected during the baseline year using four 24-hour telephone recalls, each recall spaced approximately 3 months apart. Data have recently become available for baseline data collection and subsequent clinical exam visits that include anthropometry and Tanner stage assessment. Preliminary analyses of data from the San Francisco Bay Area suggest phytoestrogen intake may be associated with delayed onset of puberty, but this observation needs to be confirmed with more rigorous data analysis and inclusion of data from Cincinnati and New York. Results from these analyses will be presented, along with a broader overview of dietary factors in breast cancer and the role of the BCERCs in examining the role of diet and other environmental factors in the development of breast cancer.
Supported by the UCSF Breast Cancer and the Environment Research Center.