A BREAKDOWN product of a common oestrogen replacement therapy can bind to
DNA. This may help to explain why excess oestrogen can cause breast cancer.
A woman鈥檚 risk of breast cancer is known to rise as her exposure to oestrogen
increases. Researchers suspected that this is because oestrogen overstimulates
receptors on cells, or because its breakdown products cause mutations in
DNA.
Judy Bolton and her colleagues at the University of Illinois in Chicago
report evidence to support the second theory in next month鈥檚 Chemical
Research in Toxicology. They synthesised a breakdown product of the widely
prescribed drug Premarin and found that it binds to DNA in vitro.
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鈥淲e鈥檝e shown that, chemically, it鈥檚 possible,鈥� says Bolton. However, she
stresses that no one yet knows if this happens in the body.