An estimated 12.4% of women born in the US today will develop breast cancer at some point during their lives. Past research has indicated that exposure to some chemicals may increase the risk of breast cancer. Now, a new study has identified 17 “high-priority” chemicals women should avoid in order to reduce such risk and demonstrates how their presence can be detected.
Scientists from the Silent Spring Institute in Massachusetts say their findings, recently published in Environmental Health Perspectives – a journal from the National Institutes of Health (NIH) – significantly advance breast cancer prevention efforts.
“The study provides a road map for breast cancer prevention by identifying high-priority chemicals that women are most commonly exposed to and demonstrates how to measure exposure,” explains study author Ruthann Rudel, research director of the Silent Spring Institute.
“This information will guide efforts to reduce exposure to chemicals linked to breast cancer, and help researchers study how women are being affected.”
According to the research team, only 5-10% of breast cancers are a result of high-risk inherited genes. Furthermore, they note that around 80% of women diagnosed with breast cancer are the first in their family to develop the disease. Such figures, the researchers say, are evidence that breast cancer is caused by additional factors.
Identifying breast cancer carcinogens
It is well documented that exposure to some chemicals, including alcohol, tobacco smoke and those involved in combination hormone replacement therapy, may increase the risk of breast cancer in women.
But the researchers note that many other chemicals have been shown to cause mammary tumors in animals. However, only a small number of these chemicals have ever been incorporated in human breast cancer studies, partly because there have been no reliable techniques through which to measure exposure.
Therefore, the team set out to determine what chemicals present the highest risk of breast cancer in women and how exposure to such chemicals can be measured.
Firstly, the researchers identified 216 chemicals that have been associated with mammary tumors in rodents, before identifying 102 that women were most likely to be exposed to.
The team then reviewed exposure to such chemicals in rodent studies and compared the results with human breast cancer studies. This was to see whether rodent studies could be used to predict human study results.
The researchers assessed studies in which researchers had measured breakdown products (metabolites) of each chemical or the chemical itself in the blood, urine or other samples of humans. This was to determine the best way for researchers to measure exposure to carcinogens.