New Delhi: Women exposed to higher levels of two common ‘forever chemicals’ may face an increased risk of developing an aggressive form of breast cancer, according to a new study conducted by researchers at the US National Institutes of Health, or NIH.
Published in the Journal of Clinical Oncology on 5 November, it found that women with higher blood concentrations of perfluorooctanoic acid (PFOA) and perfluorooctanesulfonic acid (PFOS) were more likely to develop estrogen receptor-negative (ER-negative) breast cancer.
“Our findings, which we confirmed using a meta-analysis of prior research, indicate that certain legacy PFAS, including PFOA and PFOS, are associated with a higher risk of ER-negative breast cancer,” said lead researcher Alexandra White.
What are forever chemicals?
Per- and polyfluoroalkyl substances (PFAS), the larger group under which both PFOA and PFOS come under, are synthetic chemicals used in various consumer and industrial products. They are commonly called ‘forever chemicals’ because they break down slowly and can persist in the human body and wider environment for years.
PFOA and PFOS are particularly common variants of forever chemicals because they are water-soluble and can travel very long distances through various environments via soil and water. According to toxicology reports in the US, they are prevalent in over 95 per cent of the population. India has attempted to regulate, but has not banned, the use of these particular forever chemicals.
ER-negative breast cancers lack receptors for estrogen, a hormone that can stimulate the growth of certain breast tumours. These cancers are generally more aggressive and have fewer established risk factors than ER-positive cancers.
What did the researchers find?
The researchers analysed blood samples collected from participants in the Sister Study, a long-running American prospective cohort study involving 50,884 women aged 35-74 who had a sister diagnosed with breast cancer.
The latest analysis included 1,609 women who developed breast cancer during the study, and a comparison sample of 2,269 participants drawn from the larger study population. The researchers measured 17 forever chemicals in the blood collected prior to the former group’s cancer diagnoses.
Women with the highest PFOA concentrations had a 67 per cent higher rate of ER-negative breast cancer compared with those with the lowest concentrations. Those with the highest PFOS levels had a 93 per cent higher rate.
However, the researchers could not find clear association between either chemical and overall breast cancer incidence.
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Could reducing exposure help?
“Although PFAS are persistent in the environment and in our bodies, exposure to them is still potentially modifiable,” first author Che-Jung Chang said, suggesting that the findings could inform future prevention strategies.
The researchers proposed that PFAS might influence cancer development through changes in gene activity or immune function, although these mechanisms were not directly investigated.
The study was observational and therefore could not establish whether PFAS exposure caused breast cancer. Its participants, having been part of the Sister Study, also had a family history of the disease, potentially limiting how broadly the findings can be applied.
“More research is needed, particularly evaluating the risk of breast cancer associated with newer replacement PFAS chemicals,” White said.
(Edited by Aamaan Alam Khan)