Antiprogestins reduce epigenetic field cancerization in breast tissue of young healthy women

Breast cancer is a leading cause of death in premenopausal women. Progesterone drives expansion of luminal progenitor cells, leading to the development of poor-prognostic breast cancers. However, it is not known if antagonising progesterone can prevent breast cancers in humans. We suggest that targeting progesterone signalling could be a means of reducing features which are known to promote breast cancer formation. Overall design: Core needle breast biopsies collected at baseline and after two months of 50 mg mifepristone treatment every other day from healthy women (n=16), aged 18-35 years, with regular menstrual cycles and with no hormonal treatment. BRCA1/2 mutation status was not assessed for these subjects.