The Institute of Medicine (IOM) Committee on Breast Cancer and the Environment: The Scientific Evidence, Research Methodology, and Future Directions are pleased to announce the release of its report, Breast Cancer and the Environment: A Life Course Approach. The report is available for free download at www.iom.edu/BreastCancerEnvironment. Also available are a 4-page Report Brief and a Question and Answer Booklet for a general audience. A brief description of the report is provided here.
Many wonder about the role environmental factors may be playing in breast cancer. Susan G. Komen for the Cure® and its Scientific Advisory Board commissioned a study by the IOM to review current evidence on the contribution of environmental exposures, alone or in combination with genetic factors, to the risk of developing breast cancer; review the challenges in studying this topic; explore evidence-based actions that women might take to reduce their risk of breast cancer; and recommend research directions.
The committee defined "environment" broadly and reviewed evidence on a range of factors women encounter in their daily lives. Of the environmental factors the committee reviewed, some of those with the most consistent evidence of a link with increased breast cancer risk included ionizing radiation, combination estrogen-progestin hormone therapy, and greater postmenopausal weight. More physical activity was linked to reduced risk. For many other factors, however, the evidence from human studies is more limited, contradictory, or absent.
Knowledge about the complexity of breast cancer and its relation to environmental exposures continues to grow, but researchers face many challenges in trying to learn more. These challenges include understanding the biologic significance of the life stages at which environmental risk factors are encountered; integrating analysis of genetic and environmental influences; determining the possible effects of combinations of multiple low-level chemical exposures; and interpreting findings from studies in animals and in vitro systems.
The committee concluded that women may have some opportunities to reduce their risk of breast cancer through personal actions, such as avoiding unnecessary medical radiation throughout life, avoiding use of estrogen–progestin hormone therapy, avoiding smoking, limiting alcohol consumption, increasing physical activity, and, for postmenopausal breast cancer, minimizing weight gain. Research recommendations include applying a life course approach to studies of breast cancer, developing improved tools for epidemiologic research and testing of chemicals and other substances, developing effective preventive interventions, developing better approaches to modeling breast cancer risks, and improving communication about breast cancer risks.
Dr. Robert Hiatt, Professor and Chair, Department of Epidemiology and Biostatistics at UCSF is a member of this committee.