The link between breast cancer and estrogen is already established, but now scientists at the Genome Institute of Singapore (GIS), a biomedical research institute of the Agency for Science, Technology and Research (A*STAR), and the Karolinska Institutet, Sweden, have made a new discovery. They have found that DNA polymorphisms related to the production of estrogen play an important role in the development of hormone-sensitive breast and endometrial cancer.
They hope that the knowledge gained may help develop better measures for the prevention and treatment of breast and endometrial cancers. What is impressive about this study is that it is the most comprehensive genetic research into the estrogen metabolism pathway – involving 7577 participants from Sweden and Finland. Too many studies, in my opinion, are of a small and limited scale but this one is able to overcome many limitations of previous studies which have typically looked at single genes and have produced inconsistent results.
Genes work together in complex networks. By using a systematic approach to interrogate the network of genes that affects hormonal exposure and hence risk of breast and endometrial cancers, they found a small group of genes which work together to affect cancer risk.
This may seem academic but the results of this study have moved us one step closer to understanding the common pathways which are involved in the development of breast cancer and endometrial cancer and raise the possibility of having a test using multiple genetic markers that, when added together, can give an estimate of risk for the most common forms of breast cancer.
Previously such genetic risk determination was limited to rare forms of breast cancer. The scientists found a positive association of breast cancer risk with the DNA variation of the genes involved in the production of estrogen, including the CYP19A1 gene that produces aromatase enzyme. This enzyme is used to produce estrogen from androgen in postmenopausal women. As estrogen exposure is the most important risk factor for breast cancer, inhibiting aromatase activity and thus lowering estrogen production has been commonly used to treat breast cancer in postmenopausal women.
The finding of this study raises the possibility that breast cancer can be prevented by blocking the production of estrogen through the use of an aromatase inhibitor.