Skip Navigation

Your Environment. Your Health.

Breast Cancer

Table of Contents


Breast Cancer Awareness: Prevention is the Key

The National Institute of Environmental Health Sciences (NIEHS) joins individuals and organizations across the U.S. in support of Breast Cancer Awareness month throughout October.


NIEHS supports research that is helping to discover how our environment may contribute to diseases such as breast cancer.

Once scientists can identify risk and protective factors associated with breast cancer, appropriate interventions and precautions can be developed.

According to the National Cancer Institute in 2014 there were an estimated 232,670 new cases (female) and 2,360 (male) from breast cancer and more than 40,000 deaths. It is estimated that environmental factors account for at least 2/3 of cancer cases in the United States. Environmental factors are more readily identified and modified than genetic factors, presenting us with a tremendous opportunity to prevent breast cancer.

Research from NIEHS and other NIH institutes and entities are providing new information that can help prevent this disease. Our grantees and partners across the nation are making great efforts to translate breast cancer research findings into messages that lead to action.

IBCERCC Report Cover


A report released in 2013, Breast Cancer and the Environment: Prioritizing Prevention(5MB), by the Interagency Breast Cancer and Environmental Research Coordinating Committee (IBCERCC) highlights the need for more emphasis on prevention—not just diagnosis and treatment—and suggests that a national breast cancer prevention strategy be developed that would increase and better coordinate the federal government’s investments in this area. NIEHS and its partners are putting this plan into action.

What NIEHS is doing on Breast Cancer

All divisions within NIEHS are involved with breast cancer research. What follows are some recent highlights from the breadth of the NIEHS research portfolio, which includes activities led by:

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

Given that NIEHS research has clearly established that breast cancer is caused by a combination of genetic, hormonal, and environmental risk factors and we know that environmental factors can be identified and modified, focusing our efforts on prevention presents a tremendous opportunity to stop breast cancer before it starts.

In-house Led Efforts — Updates from the Sister Studies

Two Sister Study Photo

The NIEHS-led Sister Study is the only long-term study in the United States and Puerto Rico of women ages 35 to 74 whose sisters had breast cancer. The study is following 50,000 women for at least 10 years to learn how environment and genes may affect the chances of getting breast cancer.

The Sister Study and the related Two Sister Study reported a number of important findings this year, including:

  • Solvents and breast cancer risk. Women who use solvents in their jobs may have a higher risk for breast cancer, especially if this use took place before their first full-term childbirth. Solvents are chemicals in paints, adhesives, degreasing agents, and cleaning products. The researchers found that women who worked with solvents before their first full-term birth had about a 40-percent higher risk for developing hormone-related invasive breast cancer. The researchers did not find an increased risk for invasive breast cancer from lifetime exposure to solvents. The study increases our understanding about how the timing of chemical exposure may affect breast cancer risk.  (Abstract) (Environmental Factor story)
  • Mom’s family history matters. Researchers have found that variations in genes inherited from the mother’s side of the family may influence the development of breast cancer.  Using family history data from Sister Study participants, the scientists found that breast cancer was more likely to have been diagnosed in the maternal grandmother (mother’s mother) than the paternal grandmother (father’s mother). (Abstract)
  • Cancer, aging and DNA methylation. Researchers may have one reason why cancer incidence increases with age. Using blood samples from Sister Study participants, researchers looked at methylation changes, or changes in a person’s DNA that affects how genes function in the body, in thousands of different genes and compared these results to other studies. They found specific changes in DNA methylation that became more common with increasing age. These age-related methylation sites have been reported to be more common in persons with a variety of cancers.  (Abstract) (Environmental Factor story) (Animation)
  • DNA methylation and breast cancer.  Decreases in global DNA methylation is a common feature of some cancers.  Researchers compared global methylation in 294 women who developed breast cancer after enrolling in the study and 646 other women from the cohort.  Breast cancer risk increased with decreasing levels of global methylation.  Results suggest that changes in methylation are a mechanism that could connect environmental exposures to breast cancer risk.  (Abstract)

Grantee Supported Research – Updates from the Breast Cancer and the Environment Research Program

Breast Cancer & the Environmental Research Centers: Girls

Since 2003, NIEHS and the National Cancer Institute have co-funded the Breast Cancer & the Environment Research Program, which has brought together epidemiologists, basic scientists, and community educators to identify, conduct, and share research focused on making discoveries that can help prevent breast cancer.

In November, researchers working in the Centers program will join with other scientists, community members, breast cancer advocates and others at the annual meeting to talk about new science and new opportunities.

The program has been very successful in increasing our understanding of the environmental influences, particularly early life exposures, on breast cancer risk. For example:

  • Body Mass Index and High Fat Diets. Earlier onset of puberty in girls, as indicated by the start of breast development, is strongly associated with greater body mass index (BMI). (Abstract) Also, research in rats has shown that high fat diets can increase breast cancer risk. (Abstract)
  • Endocrine Disruption. When hormone-mimicking chemicals such as BPA are given to pregnant rats, their pups have increased risk for breast cancer. (Abstract) Then, with continued exposure to BPA, the risk for breast cancer further increases, suggesting multiple windows of susceptibility after birth and throughout puberty. (Abstract)
  • New treatment targets. The discovery that the gene GATA3 is the master regulator in mammary gland development is a tremendous step forward for all breast cancer researchers and points us to a new target for therapeutic intervention for breast cancer. (Abstract)

Hear an Update on Breast Cancer Research Progress on October 20

On Monday, October 20, 2014, The Collaborative on Health and the Environment hosted a partnership call titled "Four Years after the President's Cancer Panel Report: Recommendations and Next Steps."

Suzanne Fenton, Group Leader for NIEHS and NTP Reproductive Endocrinology efforts was a guest speaker. Fenton and her group focuses on the role of environmental chemicals in breast developmental timing as it relates to puberty, increased susceptibility to breast cancer, and altered lactational ability. They provides expertise in the use of whole mount preparations in evaluating early life development of both male and female rat offspring and lifelong effects in female mice.

To hear what Fenton and others had to say, visit:

Partnerships for Environmental Public Health (PEPH)

PEPH is a network of scientists, community members, educators, healthcare providers, public health officials, and policymakers who share the goal of increasing the impact of environmental public health research at the local, regional, and national level.

One example of this program’s efforts with support from the breast cancer and environment research program is the development of a website tailored to educating young African American women about environmental risk factors for breast cancer. The site was developed by researchers, library staff, and community engagement experts associated with the University of North Carolina.

The website includes videos featuring young black breast cancer survivors, breast cancer advocates, and physicians, and shares information on breast cancer risk factors, including a tool that can help users assess personal risk. Women of all backgrounds will find the site helpful.

National Toxicology Program

NTP logo

The National Toxicology Program (NTP) is an interagency program housed at NIEHS whose mission is to evaluate agents of public health concern by developing and applying tools of modern toxicology and molecular biology. Some of the efforts it is involved with have a direct impact on breast cancer research.

The Report on Carcinogens (RoC)  is a congressionally mandated, science-based, public health document that is prepared for the Health and Human Services Secretary by the NTP. The report identifies agents, substances, mixtures, and exposure circumstances that are known or reasonably anticipated to cause cancer in humans. On October 2, 2014, the 13th edition of the RoC was released, bringing the total listings to 243. These include - alcohol beverage consumption, diethylstilbestrol, steroidal estrogens used in estrogen replacement therapy, tobacco smoking and X- and gamma-radiation – all of which have been linked to breast cancer in human studies.

The NTP Monograph on Developmental Effects and Pregnancy Outcomes Associated with Cancer Chemotherapy Use During Pregnancy released in 2013 helps pregnant women diagnosed with cancer and their medical teams make informed decisions about cancer treatment options during pregnancy. The NTP analyzed more than 430 published studies to develop this resource. The monograph includes data and summaries on 56 cancer chemotherapeutic agents administered to pregnancy cancer patients for which pregnancy outcomes were reported.

Moving Forward: NIEHS Strategic Plan

NIEHS Strategic Plan - cover

Research into environmental contributors to disease are a key part of NIEHS' new strategic plan. As laid out in the plan, NIEHS will continue work to study basic mechanisms and windows of susceptibility, and link individual and population exposure to risk using better predictive models and 21st century tools. Also, to enhance diversity in all aspects of research, NIEHS is actively involved in training multidisciplinary scientists. The institute is also enhancing coordination and communication with agencies and other groups. start comment

Back to Top

Share This Page:

Page Options:

Request Translation Services