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Your Environment. Your Health.

Breast Cancer

Introduction

woman breast cancer patient

You Can't Change Your Genes, but You Can Change Your Environment

Identifying and modifying environmental risk factors for breast cancer presents a tremendous opportunity to prevent breast cancer.

About 12%, or 1 in 8, women in the U.S. will develop breast cancer during their lifetime. It is the second most common cancer among U.S. women, behind skin cancer. Breast cancer occurs mostly in women, but men can also develop the disease.1

Breast cancer starts when cells begin to grow out of control. These cells normally form a tumor. If the cancerous cells spread to other parts of the body, it is called metastatic breast cancer.

Although scientists have identified many risk factors that increase a woman’s chance of developing breast cancer, they do not yet know what causes normal cells to become cancerous. Most experts agree that breast cancer is caused by a combination of genetic, hormonal, and environmental factors.

However, most women who develop breast cancer have no family history of the disease, suggesting an environmental link. Since environmental factors can sometimes be identified, and lifestyles modified to avoid them, NIEHS scientists and other experts in the field believe that prevention strategies are the best way to try to stop breast cancer before it starts.

What is NIEHS Doing?

For years, NIEHS has played a leadership role in funding and conducting studies on the ways in which environmental exposures increase breast cancer risk. This research includes animal studies to understand the role of environmental agents in the initiation and progression of cancer, as well as research on chemical risk factors and genetic susceptibility in humans.

Sister Study – The NIEHS Sister Study has recruited more than 50,000 sisters of women with breast cancer from the U.S. and Puerto Rico. This landmark observational study is looking at lifestyle and environmental exposures, as well as genetic and biological factors that may increase breast cancer risk. The study has been documenting some interesting findings.

Visit the Join an NIEHS Study Website

The following clinical trials are currently recruiting

  • Women who lived in areas of higher airborne lead, mercury, and cadmium were at a higher risk of developing postmenopausal breast cancer.2
  • Young women with high body fat have a decreased chance of developing breast cancer before menopause.3
  • Postmenopausal women who had higher vitamin D blood levels or who reported taking vitamin D supplements at least four times a week had lower rates of breast cancer.4
  • Burning wood or natural gas indoors, at least once a week, was associated with a modestly higher risk of breast cancer.5
  • Women who developed diabetes during two or more pregnancies had a higher incidence of breast cancer.6
  • Women who exercised or played sports more than seven hours a week when they were aged 5-19 had lower risk of breast cancer as adults.7
  • While many measures of sleep quality were not associated with breast cancer risk, there was an association between having trouble sleeping four or more nights per week and increased breast cancer risk.8
Roughly 1 in 8 U.S.women will develop invasive breast cancer sometime during her life. (American Cancer Society, 2015)
Roughly 1 in 8 U.S.women will develop invasive breast cancer sometime during her life. (American Cancer Society, 2015)

Two Sister Study – An offshoot of the Sister Study, this study focuses on breast cancer in women younger than 50, who may have different breast cancer risk factors than older women. Approximately 1,300 women with young-onset breast cancer are participating, along with their sisters from the Sister Study and their biological parents. Some results from the study include the following.

  • Women who have taken estrogen-only hormone therapy had a 42 percent decrease in their risk of young-onset breast cancer, compared to their sisters who never had hormone therapy.9
  • In a study of young-onset breast cancer, three novel single nucleotide polymorphisms,  or genetic variation, were found to be associated with the disease in younger women.10

Breast Cancer and the Environment Program (BCERP) – Jointly funded by NIEHS and the National Cancer Institute, grant-funded researchers and community organizations work together through BCERP to discover environmental factors that may contribute to breast cancer. They also share lessons learned with the broader community. Some hallmark findings from BCERP include the following.

  • Exposures to common contaminants in the environment may change the timing of puberty. For example, girls exposed to high levels of triclosan, a chemical used in antimicrobial soaps and hand sanitizers, experienced early breast development. Also, girls exposed to high levels of benzophenone-3, found in some sunscreens, experienced later breast development.11
  • Proteins produced by developing mammary tissue may change after exposure to pollutants in the environment, including bisphenol A, a chemical found in many plastic products. These exposures may alter cells in ways that contribute to breast cancer.12

National Toxicology Program (NTP) – Headquartered at NIEHS, NTP is an interagency program known for its expertise in conducting studies that help gain insights into the environmental origins of disease, including breast cancer. For example, researchers in the Reproductive Endocrinology Group are working to establish new methods to study mammary glands that can be used and compared across other labs. This will help scientists accurately identify environmental factors that may lead to problems in mammary development or function.

The Interagency Breast Cancer and Environmental Research Coordinating Committee (IBCERCC)
Supported by NIEHS and the National Cancer Institute, IBCERCC was a congressionally mandated committee that was formed to examine the state of research on breast cancer and the environment in response to the Breast Cancer and Environmental Research Act of 2008. The committee included federal and non-federal representatives.

In 2013, IBCERCC issued a comprehensive report to the secretary of the U.S. Department of Health and Human Services that recommended prioritizing prevention to reduce breast cancer, intensifying the study of chemical and physical risk factors, transforming research to include collaborations across scientific disciplines and with community organizations, and communicating the science to the public.

Further Reading

Additional Resources

Fact Sheets

Breast Cancer Risk and Environmental Factors

Related Health Topics


  1. American Cancer Society. 2018. Breast Cancer [accessed December 3, 2018]. [Available American Cancer Society. 2018. Breast Cancer [accessed December 3, 2018].]
  2. White AJ, O'Brien KM, Niehoff NM, Carroll R, Sandler DP 2018. Metallic Air Pollutants and Breast Cancer Risk in a Nationwide Cohort Study. Epidemiology; doi:10.1097/EDE.0000000000000917 [Online December 2018]. [Abstract White AJ, O'Brien KM, Niehoff NM, Carroll R, Sandler DP 2018. Metallic Air Pollutants and Breast Cancer Risk in a Nationwide Cohort Study. Epidemiology; doi:10.1097/EDE.0000000000000917 [Online December 2018].]
  3. Premenopausal Breast Cancer Collaborative Group et al. 2017. Association of Body Mass Index and Age With Subsequent Breast Cancer Risk in Premenopausal Women. JAMA Oncol; doi:10.1001/jamaoncol.2018.1771 [Online 1 November 2018]. [Abstract Premenopausal Breast Cancer Collaborative Group et al. 2017. Association of Body Mass Index and Age With Subsequent Breast Cancer Risk in Premenopausal Women. JAMA Oncol; doi:10.1001/jamaoncol.2018.1771 [Online 1 November 2018].]
  4. O’Brien KM, Sandler DP, Taylor JA, Weinberg CR. 2017. Serum Vitamin D and Risk of Breast Cancer within Five Years. Environ Health Perspect 125(7):077004. [Abstract O’Brien KM, Sandler DP, Taylor JA, Weinberg CR. 2017. Serum Vitamin D and Risk of Breast Cancer within Five Years. Environ Health Perspect 125(7):077004.]
  5. White AJ, Sandler DP. 2017. Indoor Wood-Burning Stove and Fireplace Use and Breast Cancer in a Prospective Cohort Study. Environ Health Perspect 125(7):077011. [Abstract White AJ, Sandler DP. 2017. Indoor Wood-Burning Stove and Fireplace Use and Breast Cancer in a Prospective Cohort Study. Environ Health Perspect 125(7):077011.]
  6. Park YM, O’Brien KM, Zhaos S, Weinberg CR, Baird DD, Sandler DP. 2017. Gestational diabetes mellitus may be associated with increased risk of breast cancer. Br J Cancer 116(7):960-963. [Abstract Park YM, O’Brien KM, Zhaos S, Weinberg CR, Baird DD, Sandler DP. 2017. Gestational diabetes mellitus may be associated with increased risk of breast cancer. Br J Cancer 116(7):960-963.]
  7. Neihoff NM, White AJ, Sandler DP. 2017. Childhood and teenage physical activity and breast cancer risk. Breast Cancer Res Treat 164(3):697-705. [Abstract Neihoff NM, White AJ, Sandler DP. 2017. Childhood and teenage physical activity and breast cancer risk. Breast Cancer Res Treat 164(3):697-705.]
  8. White AJ, Weinberg CR, Park YM, D’Aloisio AA, Vogtmann E, Nichols HB, Sandler DP. 2017. Sleep characteristics, light at night and breast cancer risk in a prospective cohort. Int J Cancer 141(11):2204-2214. [Abstract White AJ, Weinberg CR, Park YM, D’Aloisio AA, Vogtmann E, Nichols HB, Sandler DP. 2017. Sleep characteristics, light at night and breast cancer risk in a prospective cohort. Int J Cancer 141(11):2204-2214.]
  9. O’Brien KM, Fei C, Sandler DP, Nichols HB, DeRoo LA, Weinberg CR. 2015. Hormone therapy and young-onset breast cancer. Am J Epidemiol 181(10):799-807. [Abstract O’Brien KM, Fei C, Sandler DP, Nichols HB, DeRoo LA, Weinberg CR. 2015. Hormone therapy and young-onset breast cancer. Am J Epidemiol 181(10):799-807.]
  10. O’Brien KM, Shi M, Sandler DP, Taylor JA, Zavkin DV, Keller J, Wise AS, Weinberg CR. 2016. A family-based, genome-wide association study of young-onset breast cancer: inherited variants and maternally mediated effects. Eur J Hum Genet 24(9):1316-1323. [Abstract O’Brien KM, Shi M, Sandler DP, Taylor JA, Zavkin DV, Keller J, Wise AS, Weinberg CR. 2016. A family-based, genome-wide association study of young-onset breast cancer: inherited variants and maternally mediated effects. Eur J Hum Genet 24(9):1316-1323.]
  11. Wolff MS, Teitelbaum SL, McGovern K, Pinney SM, Windham GC, Galvez M, Pajak A, Rybak M, Calafat AM, Kushi LH, Biro FM, Breast Cancer and Environment Research Program. 2016. Environmental phenols and pubertal development in girls. Environ Int 84:174-180. [Abstract Wolff MS, Teitelbaum SL, McGovern K, Pinney SM, Windham GC, Galvez M, Pajak A, Rybak M, Calafat AM, Kushi LH, Biro FM, Breast Cancer and Environment Research Program. 2016. Environmental phenols and pubertal development in girls. Environ Int 84:174-180.]
  12. Williams KE, Lemieux GA, Hassis ME, Olshen AB, Fisher SJ, Werb Z. 2016. Quantitative proteomic analyses of mammary organoids reveals distinct signatures after exposure to environmental chemicals. Proc Natl Acad Sci USA 113(10):E1343-E1351. [Abstract Williams KE, Lemieux GA, Hassis ME, Olshen AB, Fisher SJ, Werb Z. 2016. Quantitative proteomic analyses of mammary organoids reveals distinct signatures after exposure to environmental chemicals. Proc Natl Acad Sci USA 113(10):E1343-E1351.]

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