Breast Cancer And Progesterone

Bioidentical doctors have been saying for years how protective progesterone is for breast cancer. Now research seems to have ‘discovered’ it but are we talking about the same thing?


There are around 55,200 new breast cancer cases in women in the UK every year (2016-2018), and also approximately 370 men are also diagnosed was well.

There is good news in that the average 5-year survival rate for women with non-metastatic invasive breast cancer is 90%.

The average 10-year survival rate for women with non-metastatic invasive breast cancer is 84%.

If the invasive breast cancer is located only in the breast, the 5-year survival rate of women with this disease is 99%.

So can you do anything to improve on those statistics?

Progestins or progesterone?

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 Dame Dr Shirley Bond and Dr Tony Coope have advocated the use of bioidentical progesterone to help oppose the excess oestrogen that is linked to such hormonal cancers.

Now it seems that medical science has caught up as Cambridge University researchers have shown that ‘progesterone’ slows the growth of tumours. Or have they?

As they also state that it is an’ inexpensive drug used in contraceptives’,  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 55,200 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

A simple way to protect yourself from breast cancer risk 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. Next 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.

What you need to ensure that it is the real hormone, and not a synthetic progestin, that is being used in any treatment regime.

Helpful information

Good hormone levels are essential to good health, and particularly in the case of all hormonal cancers, and it is progesterone that is the vital hormone to oppose excess oestrogen.

The book ‘What Your Doctor May Not Tell You About Breast Cancer’ by John Lee MD is available as a Kindle or paperback.