Bioidentical Hormones & Cancer

I am frequently asked by women who have a history of cancer whether bio identical hormones are safe to use so Dr Tony Coope shares his view.


Clearly, this is a topic that causes concern as the options for treatment of breast cancer often include drugs such as Tamoxifen, and so women ask whether or not they can safely use bioidentical hormones as well.

I thought it was important to get an expert, medical, view on this and so I asked a colleague Dr Tony Coope and here he discusses the use of progesterone and combined creams in women with a past history of cancer of the breast, endometrium or ovaries.


There seems to be a quite widely held assumption among doctors, cancer charities and others that the hormones that facilitate the growth of ‘hormone-dependent’ cancers such as breast, ovary and the uterine endometrium include both oestrogen and progesterone, – the cancer cells being found to be ‘receptor ER positive’ and /or receptor PR positive’ respectively.

However, the physiology of these hormones shows that they are ‘oppositional’, – one of oestrogen’s functions is to facilitate the growth and multiplication of cells (if there are enough oestrogen receptors to receive the message), whereas progesterone inhibits or reverses this, again subject to sufficient receptors.

This is seen clearly in the regulation of a woman’s normal menstrual cycle.

Regulating the growth rate of hormonal cancers

For me this explains in part the problem of the different degrees of ‘aggressiveness’, both local and metastatic, of these cancers. These hormones are not in themselves their cause, but they do play a significant part in regulating their rate of growth. Thus an ER- and PR+ cancer should be slow-growing, an ER- and PR- slightly more rapid, (the degree of this depending on the relative proportion of oestrogen and progesterone receptors and the relative levels of the available hormones in the body), and an ER+ / PR- the most aggressive.

However, because there are a number of other important factors that influence the rate of proliferation, insulin-like growth factor among them, one does not always see the correlation that one might expect, such as the ER- and PR- combination often being linked with the worst outcomes.

Maintaining hormone balance

So it’s all about balance; if with a past history of one of these cancers, there are severe flushes or vaginal atrophy (oestrogen deficiency symptoms), then it is important that these women are given oestrogen balanced by bioidentical progesterone, not synthetic progestins which are not the same.

Vaginal atrophy in particular can very safely be treated with direct application of oestriol or oestradiol preparations, as almost all will be absorbed locally where it is needed.

The addition of bio-identical progesterone via skin application would indeed provide a further level of protection.

Lastly, bioidentical progesterone has the benefits of Tamoxifen in cancer protection, WITHOUT any of the side effects, which are listed as:-

  • increased tumour or bone pain
  • hot flushes
  • nausea
  • fatigue
  • mood swings
  • depression
  • headache
  • hair thinning
  • constipation
  • dry skin
  • loss of libido

These are all the signs and symptoms of menopause and more.

Helpful information: 

If you are considering using bio identical hormones as discussed by Dr Coope it is always recommended that you discuss any supplementary treatment with your own doctor or consultant.

You may also be interested in the following article on the use of bioidentical progesterone, not synthetic progestins, for helping with the severe symptoms associated with such cancers and their treatment.