Breast cancer is the most common type of female cancer, affecting a staggering one in eight women across Europe and the U.S. Previous research has indicated that the contraceptive pill and hormone replacement therapy may be partly to blame for the increase. Now scientists have demonstrated how they cause breast cancer.
The synthetic female sex hormones that are present in the pill and in HRT can trigger a protein called RANKL. RANKL is normally responsible for the development of healthy bones. It activates cells that break down bone material when it needs to be replaced, thus avoiding disease in the bone and ensuring it is strong. Sometimes this process goes wrong and results in osteoporosis. The scientists then discovered that this same protein was present in breast tissue.
After testing the effects of the contraceptive pill and HRT on mice they found that the protein triggered cells to divide and multiply but they then failed to die when they should. The stem cells in the breast also became able to renew themselves. This resulted in too many cells and ultimately, breast cancer.
Instead of suggesting that women not take the pill or artificial hormone replacement therapy - both of which are unnecessary (there are alternatives), they suggest developing new drugs to suppress the action of RANKL – basically a drug to stop the effects of another drug.
“Ten years ago we formulated the hypothesis that RANKL might be involved in breast cancer and it took us a long time to develop systems to prove this idea," said Professor Josef Penninger. ” 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."