Two “forever chemicals” are linked to a higher risk of aggressive estrogen receptor-negative breast cancer, according to new research from the National Institutes of Health (NIH).
The study identifies a specific association between blood levels of PFOA and PFOS and a more difficult-to-treat subtype of breast cancer.
The findings, published in the Journal of Clinical Oncology, suggest that while these synthetic chemicals may not increase the risk of all breast cancers, they are specifically tied to the ER-negative variety.
This subtype is known for being more aggressive and having fewer known risk factors compared to cancers that respond to estrogen. Fox News reported that these chemicals, known as PFAS, are widely used in nonstick cookware, upholstery, and food packaging.
PFAS Exposure Increases ER-Negative Breast Cancer Risk
The research utilized data from the NIH’s Sister Study, a large-scale prospective cohort involving 50,884 women in the United States and Puerto Rico. Researchers analyzed 1,609 women who developed breast cancer and compared them to a sample of 2,269 women who did not. The investigators measured 17 different PFAS in blood samples collected before diagnosis.
The study found that women in the highest exposure groups for two specific substances faced significantly higher relative risks for ER-negative tumors. According to the NIH, the highest PFOA exposure group showed a 67% higher rate of ER-negative breast cancer.
The risk was even more pronounced for PFOS, with the highest exposure group showing a 93% higher rate compared to the lowest exposure group. MedPage Today noted that a meta-analysis of seven studies further supported the association for perfluoro-n-octanoic acid, and less so for perfluorooctane-1-sulfonic acid.
Clinical Mechanisms and Biological Pathways
While the study establishes an association, the authors emphasize that it does not prove causation. Tiffany Troso-Sandoval, a specialist in gynecological and breast cancer based in New York City who spent over 25 years at Memorial Sloan Kettering, also noted that forever chemicals can raise the risk of cancer.
She recommended not using plastic containers to heat food, as the process of heating these plastics can cause more of the compounds to leach into the food.
Because the strongest links were found in tumors without hormone receptors, researchers are investigating non-hormonal biological pathways. The NIH suggests these pathways could include changes in gene activity or the immune system. However, the study did not directly test these specific biological explanations.
| Chemical Compound | Associated Cancer Type | Relative Risk (Highest vs. Lowest Exposure) |
|---|---|---|
| PFOA (Perfluorooctanoic acid) | ER-negative breast cancer | 67% higher rate |
| PFOS (Perfluorooctanesulfonic acid) | ER-negative breast cancer | 93% higher rate |
| General Breast Cancer | All types | No clear association found |
Newer Replacement PFAS Chemicals Require More Research
The current research is limited by its focus on legacy PFAS—chemicals that have been largely phased out and replaced with new PFAS compounds. Alexandra White, Ph.D., an NIH Stadtman Investigator who led the study, noted that more research is needed, particularly evaluating the risk of breast cancer associated with newer replacement PFAS chemicals.
“This study, along with the accompanying meta-analysis of previous studies, provides evidence that two PFAS are related to a higher ER-negative breast cancer risk,” study leader Alexandra White, Ph.D., a researcher at the National Institutes of Health, said.
The research was supported by grants from the National Institute of Environmental Health Sciences (NIEHS). The study’s findings help bridge a gap in understanding, as ER-negative tumors are less frequently diagnosed and have historically been harder to study. MedPage Today reported that the research team specifically oversampled women with ER-negative tumors to improve the study’s statistical power.
Actionable Steps to Reduce Chemical Exposure
Although PFAS are persistent in the environment, researchers emphasize that exposure is potentially modifiable. Alexandra White pointed out that because exposure can still be modified, individuals can take action to lessen it, and these results may lead to new preventative methods.
Medical experts recommend several practical changes to minimize daily exposure:
- Cookware: Maybe consider cooking with stainless steel pots and pans.
- Food Storage: Do not use plastic containers for heating food, since the heat can cause more of these compounds to leach into your meals.
- Water Safety: Reducing exposure to sources such as contaminated water would be a very reasonable step.
- Personal Care: Review cosmetics and personal care products that may contain some of these compounds.
When to Consult a Medical Professional
While reducing environmental exposure is a proactive measure, it does not replace clinical screening.
Future research is expected to focus on the risks associated with newer replacement PFAS compounds and their specific effects on different biological pathways.
