Bioidentical Natural Progesterone or Tamoxifen To Reduce Breast Cancer Risk?

This drug finds no favour with doctors experienced in natural hormone usage, so why is it now being given permission to be used as a preventive for many more women?


The media have been full of reports that here is a drug that prevents breast cancer for 20 years: Protection for thousands at high risk is promised in new guidelines which suggest women would take the drugs for five years either before or after the menopause with the aim of slashing odds of developing the disease.

However this drug has not been licensed in the UK as a preventive treatment for breast cancer and it is known to have serious side effects and linked to an increased risk of cancer of the uterus and endometrium.

Breast cancer of course is not to be taken lightly, but nor is giving a powerful drug with serious known side effects to thousands of healthy women who may not need it. Tamoxifen is licensed in the U.S. for breast cancer prevention but is not widely taken up, partly because of concerns about side effects. In fact the World Health Organisation initially labelled Tamoxifen as a toxin and is associated with a variety of side effects. may be associated with endometrial proliferation, hyperplasia, polyp formation, invasive carcinoma, and uterine sarcoma.

So what’s new?

Tamoxifen has been used to treat breast cancer for more than 30 years, although newer drugs are proving even more effective. So why now to suggest its use proactively? Women would need to take the drugs for five years either before or after the menopause. Almost 50,000 women a year are diagnosed with breast cancer. Of these, around 2,400 have inherited faults in known breast cancer genes while a further 5,000-7,000 are affected by genes not yet identified.

Breast cancer specialist Professor Michael Baum said the drugs were a ‘reasonable option’ for women at high risk because of evidence that they cut the death rate. He said ‘I don’t think women or doctors will be deterred from using them by the lack of a licence.‘

What is being suggested is that Tamoxifen is ‘one of an array of options to help control their risk’ but there is an option that is still not being mentioned, except by Doctors familiar with bioidentical hormones.

Why to treat with caution – a Doctor’s view

Tamoxifen is one of a class of drugs known as selective estrogen receptor modulators (SERMs). Although the primary therapeutic effect of tamoxifen is derived from its antiestrogenic properties, it also does have some a estrogenic activity, and excess oestrogen is is one of the root causes of breast cancer.

The main drawback are those side effects, and they are not insignificant – particularly if you are a woman who is not at hight risk. Tamoxifen may be associated with endometrial proliferation, hyperplasia, polyp formation, invasive carcinoma, and uterine sarcoma. women receiving tamoxifen.

Doctors familiar with bioidentical natural hormone usage share their views on Tamoxifen.

Dr John Lee was the pioneer of natural progesterone cream usage and it was his view that using natural progesterone would help counteract the drug’s negative side effects.

Dame Dr Shirley Bond commented: “women who feel they wish to stay Tamoxifen would be well advised to combine it with bioidentical natural progesterone. You would discuss any alternative treatment with your own doctor, but given what we know of the beneficial effects of natural progesterone and its protective role against breast cancer you may wish to consider whether you do need to take Tamoxifen as well. It remains a drug that should be taken with caution, bearing in mind its possible side effects.” In Dr Bond’s opinion

Dr Tony Coope commented: The recent discussion about possible future use of the estrogen-blocker tamoxifen (used at present in women with an established diagnosis with the aim of preventing recurrence) in women at high risk of first developing breast cancer has once again missed an essential point.

Some say that 5 years of tamoxifen in these women may reduce risk by 50-70%, while admitting that it is by no means effective for all, and cannot help women who are estrogen receptor negative (who require an alternative, an aromatase inhibitor). The essential conversion of tamoxifen by the liver into the active endoxifen may be compromised by genetic enzyme variations or by the concomitant use of SSRI antidepressants, which may be prescribed for the hot flushes, mood swings and depression caused directly by the use of tamoxifen itself.

Not only does tamoxifen have significant side effects, – the menopausal-like symptoms of hot flushes, emotional fluctuations, depression, vaginal atrophy and low libido, sleep disturbance and fatigue, but paradoxically increases the risk of endometrial cancer in women with an intact womb, and of thrombo-embolic events (stroke, heart attack and deep vein thrombosis with secondary pulmonary embolism, all of which can be fatal).

But while the relative risks versus benefits are being debated, the discussion remains firmly fixed in the realm of synthetic pharmaceutical drugs. How is it that there is never a mention of the potential of bio-identical progesterone, which nature has developed to supply all the beneficial estrogen-opposing actions required, without the unpleasant side effects and significant risks of the synthetic product?’

What’s the alternative?

As Dr Coope points out, in all the talk of preventive drug therapy, no mention has been made of bioidentical hormone treatment. Dr David Zava has been writing about the protective effect of natural progesterone for breast cancer for many years, as natural progesterone is known to have the effect of dampening down the stimulating effect of oestrogen on breast tissues. This is exactly what you wish to achieve to give yourself maximum protection against breast cancer.

Tamoxifen does have serious reported side effects as mentioned above, whereas natural progesterone does not have any reported side effects after many years of use throughout the world.

There is no doubt that Tamoxifen may help some women, but where there is information on alternatives it needs to be made more public so women can consider all their options.