Breast cancer appears when abnormal cells start growing in breast tissue and can affect both women and men. It was estimated that in the U.S. alone there will be a total of 330,080 new cases of breast cancer in women and about 2,550 in men by the end of 2018.

Scientists from Princess Margaret Cancer Centre in Toronto, Canada, have discovered that obstructing certain proteins that react to the progesterone hormone can avert breast cancer in patients who carry a heavy genetic risk.

Rama Khokha, study senior author, a senior scientist at Princess Margaret Cancer Centre and professor of biophysics at the University of Toronto, says “there are no standard of care preventative interventions for women at high risk of breast cancer."

Epigenetic proteins expand the “mammary gland stem cells” when they are exposed to progesterone. Epigenetic proteins are the basic switch that triggers the stem cell proliferation in reply to progesterone. Prof. Khokha and team noticed how mammary gland cells outlaid from mice responded to being exposed to progesterone. They paid specific attention to changes in the proteins and epigenomes of the cells. The scientists discovered that when exposed to progesterone, it triggered a huge switch-on of genes in mammary gland stem cells.

Prof. Khokha said that this made them believe that perhaps "drugs that inhibit these epigenetic regulatory proteins might suppress the proliferation of stem and progenitor cells in response to progesterone."

The scientists went on to test several "epigenetic inhibitors," many of which have already received regulatory approval for human use.