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. 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.