Research reveals potential way to prevent breast cancer in pre-menopausal women

An NHS-approved drug could be repurposed to prevent breast cancer in pre-menopausal women with a strong family history of the disease, researchers have found.

Ulipristal acetate, already prescribed on the NHS for other conditions, blocks progesterone – a hormone that can drive breast cancer development – and may help lower risk in women before the menopause.

Dr Sacha Howell is clinical senior lecturer at the University of Manchester, director of the Manchester Breast Centre and consultant oncologist at The Christie, said:

Howell said: “Our research provides evidence that progesterone plays a critical role in breast cancer development in high-risk individuals.

“By targeting its action, ulipristal acetate and other anti-progestins show promise as preventive treatments for women at increased risk.”

The study, led by University of Manchester researchers and funded by Breast Cancer Now with support from Prevent Breast Cancer, involved 24 women aged 34–44 who took the drug for 12 weeks between 2016 and 2019 at the Manchester Breast Centre.

Progesterone promotes the growth of breast cells that have the potential to turn cancerous and can also influence the environment inside the breast, making it easier for healthy cells to transform into cancer cells.

The drug specifically targeted luminal progenitor cells – the starting point for triple-negative breast cancer, a more aggressive form that is more common in younger and black women.

MRI scans showed that breast tissue became less dense after treatment – a key finding, as higher density is linked to increased cancer risk.

The effect was strongest in women who had higher breast density before treatment began.

Researchers also observed significant changes in breast tissue, including reduced levels and function of collagen proteins that normally help support breast structure.

Collagen 6 showed the most marked decrease, and researchers believe it may influence the behaviour of luminal progenitor cells.

The overall reduction made the tissue less stiff, creating an environment less favourable for cancer development.

Howell said: “What makes this study particularly exciting is the combination of clinical imaging and biological analysis, which gives us a powerful tool to understand how prevention therapies work at both the tissue and molecular levels.

“These results lay important groundwork for larger trials to confirm the potential of anti-progestins in reducing breast cancer risk.”

Dr Simon Vincent, chief scientific officer at Breast Cancer Now, which funded the research, said: “We desperately need better risk-reducing treatments for women at high risk of breast cancer that also protect their quality of life.

“And we need to explore all avenues, including existing drugs with the scope to be repurposed, to achieve this.

“Currently, these women have only two options to reduce their risk – surgery or long-term hormone therapy, both of which have a profound impact on their physical and emotional wellbeing.

“This research into ulipristal acetate is an important step forward, and aligns with our key strategic goal to accelerate the discovery of preventative treatments.

“We now need larger, longer-term studies so we can fully understand the potential of this drug to stop breast cancer developing.”