Using BHRT when you have breast cancer
Dame Dr Shirley Bond MB BS, LRCP MRCS, FFARCS
During my research, I came across some answers to questions women had asked about progesterone and breast cancer:
Can taking natural progesterone cause breast cancer?
Progesterone never causes breast cancer. If a breast cancer is described as being progesterone-sensitive, it does not mean that the progesterone caused the cancer or that the administration of progesterone will make it recur. What it means is that the breast cancer has receptors that are sensitive to progesterone. The effect of progesterone on the breast is to reduce proliferation of the tissues, and it is this proliferation that makes cancer more likely, so by using progesterone you are positively protecting your breasts against the risk of cancer.
I have been told that natural progesterone inhibits oestrogen, so can it be used instead of Tamoxifen following breast cancer?
It is not true that natural progesterone inhibits oestrogen. Oestrogen and progesterone are female hormones that occur naturally in the body and should occur in quantities that balance each other out. The importance of progesterone is that it balances out the effects of oestrogen. Breast cancer is usually an effect of oestrogen dominance. If this dominance can be counteracted, then the activity of breast cancer cells should be inhibited. It is claimed that tamoxifen does this. However, it is a very potent drug (actually a weak oestrogen) with unpleasant side effects of its own and, in the opinion of many people, is best avoided. As natural progesterone prevents oestrogen dominance and has no reported side effects, it is preferable to use it.
I had breast cancer 15 years ago and now have osteoporosis. I believe I can’t have HRT, what else can I do?
No, you will not be prescribed HRT as you would be a prime risk for further cancer if you were to be given it. However, there is still a great deal that can be done to help your osteoporosis; taking natural progesterone will enable you to build up new bone and will be protective against any further breast cancer risk.