SCIENCE: New study links breast cancer risk with EDCs
Published 1 Jun 2016
A new study has identified a strong positive association between high levels of “xenoestrogen” mixtures in blood serum and breast cancer risk. “Xenoestrogens” are endocrine disrupting chemicals that mimic oestrogen.
The research, published last week in Environmental Health Perspectives (1), measured the combined oestrogenic activity of xenoestrogens in blood serum samples taken from two groups of Spanish women. The first group had been diagnosed with breast cancer; the second was an unaffected control group. The results showed that there was a correlation between the levels of oestrogenic activity and the incidence of breast cancer. Those with breast cancer were more likely to have higher oestrogenic activity.
In order to distinguish between the oestrogenic effects caused by natural oestrogens and those caused by xenoestrogens (i.e. oestrogen mimics), the researchers used a technique known as high performance liquid chromatography. This enabled them to generate two “fractions” from the blood samples.
The “alpha” fraction contained xenoestrogens such as organochlorine pesticides, polychlorinated biphenyls, and halogenated bisphenols. The “beta” fraction included naturally occurring oestrogens and other xenoestrogens such as plant oestrogens, bisphenol A and polyphenols. The combined oestrogenic effect of all compounds included in either fraction was measured using a method known as E-Screen.
The risk for breast cancer increased with increasing levels of both alpha and beta fractions. Women in the top third of levels in the alpha fraction had a 3.45-fold increase in breast cancer risk compared to those in the bottom third. The beta fraction, that included endogenous oestrogens, was associated with a 4 fold increased risk; this was only to be expected, as a high level of oestrogen is a known risk factor for breast cancer.
Most of the women had detectable levels of various organochlorine compounds in their blood. However, no single xenoestrogen that was tested on its own was found to be significantly associated with breast cancer risk.
Interestingly, the authors also found greater effects of alpha fraction xenoestrogens on breast cancer risk in leaner women. They suggest this may be due to a greater relative impact of endocrine disrupting chemicals in women with lower levels of natural hormones, due to less fat - fat cells being a known source of oestrogen.
The results of this research highlight the importance of evaluating mixtures of endocrine disrupting chemicals when investigating their role in hormone-related cancers such as breast cancer.
Breast Cancer UK is currently supporting research which examines the effects of low dose endocrine disrupting chemical mixtures on breast morphology and carcinogenesis, using an in vitro 3D breast cell culture system
Pastor-Barriuso, R. et al. (2016). Total Effective Xenoestrogen Burden in Serum Samples and Risk for Breast Cancer in a Population-Based Multicase-Control Study in Spain. Environmental Health Perspectives. Published early online May 20, 2016. http://dx.doi.org/10.1289/EHP157