Two persistent chemicals known as PFAS may be linked to a higher risk of an aggressive form of breast cancer, according to a study by researchers at the National Institutes of Health.
PFAS are synthetic substances that degrade slowly and can accumulate in the environment and the body. They have been used in products such as nonstick cookware, clothing, upholstery, food packaging and personal care items.
The study, published in the Journal of Clinical Oncology, found that women with higher blood levels of perfluorooctanoic acid (PFOA) and perfluorooctanesulfonic acid (PFOS) were more likely to develop estrogen receptor-negative breast cancer. This subtype does not respond to estrogen and tends to be more aggressive, with poorer outcomes than some other breast cancers, according to the Department of Health and Human Services.
Researchers used data from the Sister Study, a U.S. project examining environmental and genetic factors related to breast cancer. Participants had a sister who had been diagnosed with the disease, but none had breast cancer when they joined the study.
The team tested blood samples collected before diagnosis from 1,609 women who later developed breast cancer and compared them with samples from 2,269 women. They measured 17 types of PFAS and assessed whether levels were associated with different tumor types.
Women in the group with the highest PFOA exposure had a 67% higher rate of ER-negative breast cancer than those in the lowest exposure group. For PFOS, the rate was 93% higher in the most exposed group. These are relative comparisons between groups, not estimates of any one woman’s chance of developing cancer.
The researchers did not find a clear link between either chemical and breast cancer overall. Study leader Alexandra White, a National Institutes of Health researcher, said the findings, together with an analysis of earlier research, suggest a relationship between the two PFAS and ER-negative breast cancer.
The study mainly examined older PFAS that have been largely phased out. White said relatively little is known about the chemicals now being used in their place. These newer compounds are often shorter-chain and may persist for less time in people and the environment, but their possible health effects remain uncertain.
The results show an association, not that PFAS exposure causes breast cancer. The researchers said more work is needed. Health and Human Services Secretary Robert F. Kennedy Jr. called for further investigation into how environmental chemicals may affect women’s health.
Dr. Tiffany Troso-Sandoval, a medical oncologist who specializes in breast and gynecological cancers, said PFAS can build up in the body and may contribute to cancer-related changes in cells. She noted that the study’s finding was specific to ER-negative breast cancer, an aggressive subtype, and did not show increased risk across all breast cancers.
Troso-Sandoval said PFAS might affect DNA, the body’s ability to repair DNA damage, or its capacity to eliminate cancerous cells. However, higher levels of the chemicals among patients do not establish that PFAS caused their cancers.
Study co-author Che-Jung Chang, a former NIH research fellow now working at DLH, said exposure may be possible to reduce, even though PFAS can persist in the environment and the body. She said the findings could point toward new approaches to prevention.
Troso-Sandoval advised people to consider which products they use most often and look for alternatives. She suggested stainless-steel cookware and avoiding heating food in plastic containers, since heat can increase the amount of compounds that leach into food. She also recommended checking cosmetics and personal care products for potentially concerning chemicals.
