NIH Study Links Two PFAS to ER-Negative Breast Cancer

NIH researchers found that women with higher blood levels of two widely used per- and polyfluoroalkyl substances, or PFAS, had higher rates of estrogen receptor-negative breast cancer. The study did not find a clear association between the chemicals and breast cancer overall, and its observational results do not establish that PFAS caused the cancers. In an analysis of the Sister Study, the highest blood-exposure quartile for perfluorooctanoic acid, or PFOA, was associated with a 67% higher rate of ER-negative breast cancer than the lowest quartile. For perfluorooctanesulfonic acid, or PFOS, the corresponding rate was 93% higher. These are relative comparisons between groups, not estimates of an individual woman’s absolute chance of developing the disease. The researchers included 1,609 women who developed breast cancer and a comparison group of 2,269 women. They measured 17 PFAS in blood samples collected years before diagnosis and oversampled ER-negative cases to strengthen the analysis of that less common subtype. The Sister Study had enrolled more than 50,000 women in the United States and Puerto Rico, each of whom had a sister previously diagnosed with breast cancer. The...