Progesterone And Breast Cancer

The protective role of progesterone in breast cancer prevention and treatment is well known to bioidentical doctors, and now it seems new research validates this – but are they talking about progesterone or something else?


Breast cancer is a major health concern as it claims the lives of almost 1,000 women a month. For many years researchers such as Dr Ray Peat, bioidentical pioneers such as Dr John Lee and doctors experienced in bioidentical progesterone usage such as Dr Shirley Bond have advocated the use of bioidentical progesterone to help oppose the excess oestrogen that is behind the disease.

Now it seems that medical science has caught up as newspaper reports recently reported that Cambridge University researchers have shown that progesterone slows the growth of tumours. I agree it absolutely has been shown to be effective in helping women with a history of breast cancer both preventively and after treatment to help with the side effects.

However what concerns me is that they also state that it is an inexpensive ‘drug used in contraceptives’, so yet again we have the confusion between the natural hormone progesterone and the synthetic progestin. They are not the same, progestins have their own side effects and cannot replicate the effects of the natural hormone in the way that bioidentical progesterone can.

Why bioidentical progesterone is effective

The study appears to suggest that progesterone may work in nearly half of the 55,000 cases diagnosed each year when these are oestrogen receptive. Researcher Jason Carroll said: ‘The results are pretty clear and potentially have direct benefits for many women with breast cancer.’ His research centres on tumours that are fuelled by the hormone oestrogen and in this type of tumour, progesterone ‘talks’ to the oestrogen that is trying to feed the tumour. This stops the cancer from growing as quickly.

The journal Nature has also reported tests on mice with tumours given progesterone at the same time as tamoxifen, a drug widely used after breast cancer surgery, had a dramatic effect. Cancers treated with the progesterone-tamoxifen combination grew half as quickly as those given tamixofen alone. Again this is not news to bioidentical doctors like Dr Shirley Bond who has recommended using progesterone alongside Tamoxifen to offset the side effects of the drug, particularly the horrendous hot flushes which are a common result.

What you can do

Test are being planned, but whether this is with actual progesterone or the synthetic is really not clear. What is self-evident is that a simple way to protect yourself is to tackle any oestrogen dominance to minimise the risk of breast cancer and this is best done by reducing your risk factors. Supplementing with bioidentical natural progesterone is a critical first step, as is making sure you are not overweight as that means you will be producing additional oestrogen in your fat cells, particularly after a hysterectomy and at menopause.

As almost 70 per cent of women now survive breast cancer beyond 20 years any advance in treatment is welcome, but don’t ignore the experience of the thousands of women who are already successfully using bioidentical progesterone. What we need to ensure that it is the real hormone, and not a synthetic progestin, that is being used in any treatment regime.