Joining FORCEs Newsletter

Joining FORCES is the FORCE newsletter with news, views and supportive information for individuals concerned about hereditary breast and ovarian cancer.

IOM report

Institute of Medicine Report on Environmental Causes of Breast Cancer

by Amanda Grannis

Inherited gene changes can affect the risk for breast cancer. But scientists know that there is more to cancer risk than just genes. Nongenetic factors such as hormone exposure, alcohol, chemicals, and radiation are also known to influence risk. Susan G. Komen for the Cure asked the Institute of Medicine (an independent health arm of the National Academy of Sciences) to review the current evidence on breast cancer and the environment, consider gene-environment interactions, and provide recommendations for future research. The results of this study were presented at the San Antonio Breast Cancer Symposium in December 2011.

IOM researchers are aware that breast cancer is complicated, and tying environmental factors to cancer risk is difficult because breast cancer can be triggered by multiple causes which may vary between individuals. Nonetheless, after reviewing a wide scope of scientific research and data, the study examined the interplay between environmental conditions and life stages of breast development. Certain periods of life were deemed to be 'critical windows' for personal breast cancer risk'specific episodes of hormonal change, whether in times of puberty, childbearing years, or menopause, may trigger a particular vulnerability to environmental cancer-causing exposures. The study authors emphasized that these and other age-related periods of heightened susceptibility to environmental risks might be an appropriate focus for future investigations.

Researchers formulated strategies for breast cancer risk reduction and other suggestions for future studies. While casual links between environment and breast cancer occurrence continue to be elusive, the study identified controllable lifestyle factors that can reduce a woman's odds for a breast cancer diagnosis. Researchers concluded that women can reduce their risk by limiting alcohol, abstaining from smoking, avoiding combined progesterone- estrogen hormone therapy, and exercising to control weight, especially after menopause.

Strategies for risk reduction cannot be boiled down to one-size-fits-all advice. Rather, as researchers concluded, future studies must take into account that environmental agents present varying risks according to age, development, and genetics. Scientists will need to adopt innovative approaches to study the complex and individualized impact of environmental factors on breast cancer occurrences.

Amanda Grannis is a college senior who is impacted by generations of hereditary breast cancer. Passionately committed to women's health and the courageous community of BRCA previvors and survivors, she plans to attend law school next year, pursuing a career in health law.


Breast cancer and the environment: A life course approach, consensus report from the Institute of Medicine. December 7, 2011.

Visit the website listed above for the IOM's table of risk-reducing actions. (Scroll down to 'Report at a Glance' and click on: Table: Opportunities for Action.)


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