Journal of Clinical Oncology: ‘Forever Chemicals’ Linked to Increased Risk of an Aggressive Form of Breast Cancer

The scientists analysed data from women whose blood samples had been collected several years before a possible cancer diagnosis. They found that participants with the highest levels of perfluorooctanoic acid (PFOA) had a 67% higher incidence of oestrogen receptor-negative breast cancer than women with the lowest levels of the chemical.

For perfluorooctanesulfonic acid (PFOS), the difference was 93%.

These figures represent a relative increase in the incidence of the disease between the groups, not the likelihood that an individual woman will develop cancer. At the same time, the researchers found no convincing association between levels of these chemicals and the overall risk of breast cancer.

PFAS are a large group of synthetic chemicals used in a wide range of consumer products. They are known as ‘forever chemicals’ because they break down slowly in the environment and can remain in the human body for years.

Oestrogen receptor-negative breast cancer does not depend on the stimulating effects of this hormone. These tumours are generally more aggressive and have a less favourable prognosis than hormone-dependent forms of the disease. Their causes are less well understood.

The study included 1,609 women who developed breast cancer and 2,269 participants in a control group. The authors suggest that PFAS may affect disease risk by altering gene activity or immune system function, although these mechanisms were not examined in the study.

Although PFOA and PFOS have been largely phased out, they have been replaced by other PFAS compounds whose effects on health have yet to be studied. The researchers stress the need for further research: the findings point to an association but do not yet prove that these chemicals cause cancer.