Existing NHS drug shows promise in preventing breast cancer in high-risk women
By patricklewis // 2025-11-10
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  • Researchers at the Manchester Breast Center found that blocking the hormone progesterone with the drug ulipristal acetate may help reduce breast cancer risk in premenopausal women with a strong family history of the disease.
  • Progesterone promotes growth of certain breast cells that can become cancerous and alters breast tissue to favor cancer development; ulipristal acetate counteracts these effects, offering a potential preventive approach.
  • In a clinical trial of 24 women aged 34—44, 12 weeks of ulipristal acetate treatment reduced breast density, with the greatest effect in participants who initially had high breast density—a known risk factor for breast cancer.
  • The drug also caused significant molecular changes, including reductions in collagen proteins, particularly collagen 6, which may influence luminal progenitor cells, the origin of triple-negative breast cancer.
  • Experts say the findings offer hope for safer, non-surgical risk-reducing treatments and provide groundwork for larger trials to confirm the potential of anti-progestins like ulipristal acetate in breast cancer prevention.
Researchers at the Manchester Breast Center, based at the University of Manchester, have found that blocking the effects of the hormone progesterone with a drug already available on the NHS may help reduce the risk of developing breast cancer in women before menopause who have a strong family history of the disease. The study, published in Nature, revealed that ulipristal acetate—a medication currently prescribed for other conditions—can counteract progesterone's role in breast cancer development. Progesterone promotes the growth of certain breast cells that can become cancerous and alters the breast environment in ways that make cancer more likely to form. By blocking the hormone's effects, researchers believe the drug could offer a new approach to preventing breast cancer before it starts. Between 2016 and 2019, 24 women aged 34 to 44 with a family history of breast cancer participated in a clinical trial, taking ulipristal acetate for 12 weeks. They underwent breast biopsies, blood tests and MRI scans before and after treatment. The scans showed that breast tissue became less dense—a key finding, as higher breast density is linked to greater breast cancer risk. The treatment appeared most effective in women who had high breast density at the start of the trial. The researchers also found striking biological changes in the participants' breast tissue. Treatment significantly reduced levels of collagen proteins that support breast structure, particularly collagen 6, which may influence the behavior of luminal progenitor cells—the cells thought to be the origin of triple-negative breast cancer. This aggressive cancer type is more common in younger and Black women and has a higher risk of returning or spreading in the years following diagnosis. Clinical lead author Dr. Sacha Howell, director of the Manchester Breast Center and consultant oncologist at The Christie, 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." He added that the study's combination of clinical imaging and molecular analysis "lays important groundwork for larger trials" to confirm the drug's potential.

Anti-progestin drugs could reshape breast tissue and lower cancer risk

Laboratory lead author Dr. Bruno Simões, a research fellow at the University of Manchester, explained that anti-progestins appear to reshape breast tissue at the molecular level, reducing the number of tumor-initiating cells. "We observed clear reductions in collagen levels and organization, giving us direct insight into how targeting progesterone signaling can create conditions that make it harder for cancers to develop," he said. Co-lead author Professor Rob Clarke, principal investigator and former director of the Manchester Breast Center, emphasized the collaborative nature of the work, involving researchers in Manchester, Cambridge and Toronto. "The findings reveal biomarkers that could be used to gauge response to therapy and determine whether it will be effective in preventing breast cancer," he said. Dr. Simon Vincent, chief scientific officer at Breast Cancer Now, called the results a "major step forward" in the search for safer, more effective risk-reducing treatments. "Currently, women at high risk have only two options—surgery or long-term hormone therapy—both of which can have a profound impact on their physical and emotional well-being," he said. "Research into ulipristal acetate offers real hope, but we now need larger, longer-term studies to fully understand its potential to stop breast cancer developing." The findings mark a promising advance in breast cancer prevention, suggesting that a drug already in use could one day help protect thousands of women with a heightened genetic or familial risk from developing the disease. "To prevent breast cancer, consume a diet rich in cruciferous vegetables like broccoli and cabbage, which contain sulforaphane to combat estrogen metabolism; maintain a healthy weight through regular exercise and balanced nutrition; and avoid exposure to environmental estrogens by using natural, fragrance-free personal care products and avoiding plastic containers that may leach endocrine disruptors," said BrightU.AI's Enoch. Watch and learn about five of the most powerful tools for fighting cancer.
This video is from the BrightLearn channel on Brighteon.com. Sources include: MedicalXpress.com Nature.com BrightU.ai Brighteon.com
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