How HRT and the Pill can lead to breast cancer

LONDON - Synthetic sex hormones called progestins used in hormone replacement therapy, HRT, and in contraceptives can increase the risk of breast cancers, say experts.

And now medical researchers at the Institute of Molecular Biotechnology of the Austrian Academy of Sciences in Vienna have identified a key mechanism that allows these synthetic sex hormones to directly affect mammary cells.

The research team shows that a synthetic female sex hormone used in HRT and contraceptive pills can trigger RANKL, the master regulator of healthy bones, in breast cells of mice. As a consequence, these mammary cells start to divide and multiply and fail to die when they should. Moreover, stem cells in the breast become able to renew themselves, ultimately resulting in breast cancer.

In a different set of mouse treatment tests, researchers at Amgen have found that pharmacologic blocking of the RANKL system significantly delays mammary tumor formation leading to significantly fewer breast cancers in mice. In another mouse model, RANKL inhibition not only decreased breast tumor formation but also reduced lung metastasis.

“I have to admit it completely surprised me just how massive the effects of the system were. Millions of women take progesterone derivatives in contraceptives and for hormonal replacement therapy.

Since our results show that the RANKL system is an important molecular link between a synthetic sex hormone and breast tumors, one day women may be able to reduce their risk by taking blocking medicines in advance to prevent breast cancer,” Nature quoted Prof Josef Penninger as saying.

A monoclonal antibody, denosumab, that blocks RANKL has been recently approved in the US and the EU for the treatment of osteoporosis, and is currently under review for the treatment of bone metastases in patients with advanced cancer.

This scientific article has been published on Nature’s website. (ANI)