Women with higher levels of two widely used industrial chemicals in their blood may face an increased risk of developing an aggressive form of breast cancer, according to a new federal study.
The chemicals, perfluorooctanoic acid (PFOA) and perfluorooctanesulfonic acid (PFOS), belong to a large group of man-made substances known as PFAS, commonly referred to as “forever chemicals” because they break down very slowly and can remain in the human body and environment for years.
Although PFOA and PFOS are no longer manufactured in the United States, they have been widely used in industrial and consumer products. Both have also been detected in drinking water supplies across the country.
The new research, published by the National Institutes of Health (NIH), found an association between higher blood concentrations of these chemicals and an increased risk of estrogen receptor-negative (ER-negative) breast cancer.
Researchers found that women with the highest levels of PFOA had a 67 percent higher risk of developing ER-negative breast cancer compared with women with the lowest levels. Those with the highest PFOS levels had a 93 percent higher risk.
The findings do not establish that exposure to these chemicals directly causes breast cancer, but researchers say the results highlight the need for further investigation.
“Women deserve clear answers about how chemicals in their environment may affect their health,” Health and Human Services Secretary Robert F. Kennedy Jr. said in a statement accompanying the findings.
Why ER-negative breast cancer is a concern
After a breast biopsy or surgery, cancer cells are tested for proteins known as estrogen and progesterone receptors. These receptors can help cancer cells grow and are important in determining treatment options.
Many breast cancers are hormone-receptor positive, meaning they may respond to hormone therapy. These treatments work by blocking the effects of hormones that can encourage cancer growth.
ER-negative breast cancers, however, do not have estrogen receptors and therefore do not respond to treatments that specifically target those receptors. They can also grow more quickly than some hormone-receptor-positive cancers.
According to the National Cancer Institute, ER-negative breast cancer accounts for approximately 15 percent of breast cancer cases.
Researchers believe the association identified in the new study could involve biological mechanisms beyond hormonal activity, potentially including changes in immune-system function or gene activity.
Breast cancer remains the most commonly diagnosed cancer among women in the United States, apart from skin cancers. More than 42,000 women are expected to die from the disease this year, according to the American Cancer Society.
What the study found
The research included 1,609 women who developed breast cancer and a comparison group of 2,269 women.
Researchers measured PFAS concentrations in blood samples and examined their relationship with different types of breast cancer. The analysis drew on data from the National Institutes of Health’s Sister Study, a long-term research project involving more than 50,000 women whose sisters had been diagnosed with breast cancer.
The strongest associations were observed for ER-negative breast cancer among women with the highest levels of PFOA and PFOS.
The researchers emphasized that additional studies are necessary to better understand the relationship between PFAS exposure and breast cancer risk.
“More research is needed, particularly evaluating the risk of breast cancer associated with newer replacement PFAS chemicals,” said Alexandra White, the investigator who led the research.
How to reduce exposure to forever chemicals
PFOA and PFOS can remain in the body for years, making it important to understand potential sources of exposure.
One of the first steps is finding out whether these chemicals have been detected in local drinking water.
The Environmental Protection Agency recommends that people who receive water from public systems contact their local water utility to ask whether PFAS testing has been conducted and what steps are being taken to address possible contamination.
Consumers can also consider using water filters designed to reduce PFAS, such as certain activated-carbon or reverse-osmosis systems. Bottled water may be another option, although consumers should check available information about its source and testing.
Researchers stress that the new findings point to an association rather than proof that PFAS exposure causes breast cancer. Further research will be needed to establish how these chemicals may affect cancer development and whether reducing exposure can lower the risk.
