Breast cancer patients could benefit from having the cheap and widely-available female hormone progesterone added to their treatment, according to a new UK study.
Tumours fuelled by the female hormone oestrogen are treated with drugs like tamoxifen to block oestrogen receptors, which cause cancer cells to grow.
Women whose tumours have progesterone receptors as well are known to have a better outlook. But for decades scientists have been unable to pinpoint why.
Scientists at Cancer Research UK's Cambridge Research Institute and the University of Adelaide found how the progesterone receptor 'talks to' the oestrogen receptor in breast cancer cells to change their behaviour, ultimately slowing down tumour growth.
"We've used cutting-edge technology to tease out the crucial role that progesterone receptors play in breast cancer - a mystery that has baffled scientists for many years," said Cancer Research UK's Dr Jason Carroll, who led the study with Professor Wayne Tilley at the University of Adelaide in Australia.
"This important laboratory research helps explain why some breast cancer patients have a better outlook.
"Crucially, it provides a strong case for a clinical trial to investigate the potential benefit of adding progesterone to drugs that target the oestrogen receptor, which could improve treatment for the majority of hormone-driven breast cancers," Carroll said.
There are around 50,000 new cases of breast cancer each year in the UK and around half could potentially benefit from this finding, according to the researchers.
"This exciting study in cells shows how a cheap, safe, and widely available drug could potentially improve treatment for around half of all breast cancer patients," said Dr Emma Smith, senior science communication officer at Cancer Research UK.
The research is published in the journal Nature.
