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Hormone replacement therapy and cancer – and where our new study fits in


A new study suggests it’s safe for women with ovarian cancer to take HRT. Henry French places the results in context.

Posted on 28 September, 2015 by Henry French

Newly published results of a long-term clinical trial of hormone replacement therapy (HRT) in 150 women with ovarian cancer suggest that it’s safe for these patients, and may even carry a survival benefit.

The study, led by researchers at The Institute of Cancer Research and The Royal Marsden, has clear implications for women with ovarian cancer – and it’s important to put the findings in context. The relationship between HRT and cancer is complex – and the picture is evolving as more research is carried out.

Importantly, the new research looked at the impact of HRT in patients who had been treated for ovarian cancer, rather than those yet to develop it.

Early menopause

The standard first-line treatment for many women with ovarian cancer is to surgically remove both ovaries and the womb – which begins the menopause in women yet to undergo it.

HRT can ease the symptoms of the menopause, which can be especially severe in women with ovarian cancer because it happens so suddenly. But because of previous studies linking HRT with an increased risk of developing various cancer types, women undergoing treatment for ovarian cancer (and their clinicians) have often been reluctant to use it.

Sex hormones and cancer

Whether or not taking HRT is a risk factor for women in developing cancer in the first place has been debated for many years. Sex hormones contained in HRT are known to play a role in the growth and development of some cancers, including ovarian and breast cancers.

Detailed studies have suggested use of HRT, which is usually a combination of oestrogen and progesterone, could be a risk factor for breast cancer alongside several other factors linked to hormones, such as age of first period, number of births and body mass index. Long-term use of some oral contraceptives has also been linked with an increase in breast cancer risk, but the effect diminishes rapidly after it’s stopped.

One reason why it’s been difficult for researchers to pin down the relationship between HRT and breast cancer is because even long-term use of HRT is likely to only have a slight impact on risk.

The debate has been even less clear cut in ovarian cancer – but a major study last year seemed to confirm that HRT use increases the risk a woman will develop ovarian cancer, although only by a very small amount.

And an important recent breast cancer study – involving ICR and Royal Marsden researchers – underscored the long-term benefits of aromatase inhibitors, which suppress oestrogen, in the treatment of post-menopausal women with breast cancer.

Short-term HRT use

So intriguingly we have a picture where research suggests that taking HRT could be a risk factor in developing some cancers – but in those being treated for ovarian cancer, HRT appears not to do harm and could even be beneficial.

It’s not an unexpected finding, because evidence suggests that for there to be a material increase in risk of cancer, women need to have taken HRT for several years. Short-term use, more similar to the durations used in this new study, do not appear consistently to add such a risk. The average duration of HRT treatment for women in the new trial was between one and two years.

Of course, no single study can ever give the full picture – and only time and more research will fully clarify the link between hormones and cancer.


breast cancer ovarian cancer HRT
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