PFAS and breast cancer: study links two chemicals to a type of tumor
A US National Institutes of Health analysis found an association with estrogen receptor-negative breast cancer. The results do not establish that the chemicals cause the disease.
A study published November 5 linked higher blood levels of two chemicals in the PFAS family with a higher incidence of estrogen receptor-negative breast cancer. The research, supported by the US National Institutes of Health (NIH), found no clear association between those chemicals and overall breast cancer risk.
The compounds are perfluorooctanoic acid, or PFOA, and perfluorooctanesulfonic acid, or PFOS. They belong to a large group of chemicals used in consumer products that break down slowly and can remain in the body and environment for years.
What researchers measured
The team analyzed blood samples collected before diagnosis and examined 17 PFAS. It used data from the Sister Study, a cohort that enrolled women in the United States and Puerto Rico between 2003 and 2009. Participants did not have breast cancer when they joined, but each had a sister or half-sister who had been diagnosed. The analysis included 1,609 women who developed breast cancer and a comparison sample of 2,269 participants.
According to the NIH, the rate of estrogen receptor-negative breast cancer was 67% higher in the group with the highest PFOA levels than in the lowest group; for PFOS it was 93% higher. These are relative differences between groups, not an individual’s chance of developing cancer.
What the findings show
Estrogen receptor-negative tumors lack receptors that allow estrogen to help cancer cells grow. Compared with tumors that respond to estrogen, they tend to be more aggressive, according to the NIH.
An observational design can identify an association, but it cannot by itself establish that exposure caused the tumors. Participants had a specific family history, so the findings do not necessarily describe risk across the whole population. The authors also compared their results with earlier studies in a meta-analysis.
The researchers suggest possible biological mechanisms, but the study did not test them. They also say more research is needed on PFAS that have replaced chemicals such as PFOA and PFOS, whose use has largely been phased out. The findings point to further research, not an individual test or diagnosis.
