Scientists have discovered what they claim is the first direct link between breast cancer in younger women and the sex hormone oestrogen.
An alteration in a gene involved with the breakdown of oestrogen is associated with a 9 per cent reduction in the risk of breast cancer in women aged under 51, according to their research.
The report’s senior author, Dr Olivia Fletcher from the Institute of Cancer Research, said: “This is the first time anyone has found a DNA change that is directly associated both with hormone levels and breast cancer risk in younger women.
“Scientists have suspected this link exists, but no one has been able to prove it until now.
“This represents an important step forward in our understanding of the link between hormones and breast cancer. Ultimately, it may have implications for the way we monitor and treat breast cancer.”
Researchers identified a DNA variant more common in women with lower levels of a particular oestrogen breakdown product.
Co-author Professor Isabel Dos Santos Silva, from the London School of Hygiene and Tropical Medicine, said it had been difficult to establish a link because oestrogen levels fluctuate and are were difficult to measure accurately.
She said the report, published in the Journal of the National Cancer Institute, could improve the way young women with breast cancer are diagnosed and treated.