The Impact of the Natural, Social, Built, and Policy Environments on Breast Cancer

BACKGROUND The global burden of breast cancer in women is substantial and increasing. Efforts to address breast cancer have focused on primary prevention, reduction of modifiable risk factors, early detection, timely referral for appropriate treatment, and survivorship. Environmental and lifestyle factors that increase breast cancer risk include ionizing radiation, exogenous hormones, certain female reproductive factors, alcohol and other dietary factors, obesity, and physical inactivity. A variety of chemical exposures are purported to be associated with breast cancer. METHODS In this article, we summarize the influence of the natural, social, built, and policy environments on breast cancer incidence and cancer recurrence in women based upon bibliographic searches and relevant search terms. RESULTS Despite a lack of conclusive evidence from epidemiologic studies, exposures to chemicals with estrogenic or other properties relevant to sex steroid activity could influence breast cancer risk if the exposures occur at critical life stages or in combination with exposure to other similar chemicals. Results from several studies support an association between shift work and disruption of the circadian rhythm with breast cancer risk. The social environment likely influences breast cancer risk through several mechanisms including social norms pertaining to breast feeding, age at first live birth, parity, use of oral contraceptives and replacement estrogens, diet, and consumption of alcohol. Social norms also influence body weight, obesity, and physical activity, which have an effect on risk of breast cancer incidence and recurrence. Obesity, which is influenced by the social, built, and policy environments, is a risk factor for the development of postmenopausal breast cancer and certain other cancer types. CONCLUSIONS The natural, social, built, and policy environments affect breast cancer incidence and survival. Effective health care policies can encourage the provision of high-quality screening and treatment for breast cancer and public education about the value of proper diet, weight control, screening and treatment. Additional research and policy development is needed to determine the value of limiting exposures to potentially carcinogenic chemicals on breast cancer prevention.