HRT can raise women’s risk of breast cancer, Oxford research claims

HORMONE replacement therapy increases the risk of breast cancer by a third, the most comprehensive study ever undertaken has shown.

Research by Oxford University scientists found the long-term chances of developing the disease for women on the most common form of treatment is double what was previously feared.

Experts last night called on health leaders and GPS to emphasise the risks to patients, following a tendency in recent years to downplay the link. About a million women in the UK take HRT to ease symptoms of the menopause. There was a huge uptake in the Nineties but this halved a decade later when evidence emerged suggesting a link to cancer. Numbers crept up again amid concerns that GPS were not properly setting out the risks.

Published in The Lancet, the study reviewed global evidence on HRT and found that while the general risk of breast cancer for women aged 50 to 59 who did not have HRT was 6.3 per cent, those on oestrogen plus daily progestogen – the most common form – for five years had an 8.3 per cent risk. The Oxford team believes one in 20 cases of breast cancer in the UK is due to HRT.

Prof Valerie Beral said: “Before this study all we really knew was that breast cancer risk increased while women used HRT, but the belief was it went away when they stopped. We now know the risk persists for more than a decade after stopping. We really are concerned that many GPS have been saying, ‘Oh, it’s not something you need to worry about’ – we just want GPS to quote the reliable figures.”

Women on the less common oestrogen plus intermittent progestogen regimens had a 7.7 per cent chance of developing breast cancer within 20 years, while those on oestrogen-only treatments had a 6.8 per cent chance.

Researchers said the data dispelled “myths” that women who start HRT before they turn 50 do not have an increased risk.

Data also showed there was no benefit to heart health, contrary to advice on the NHS Choices website.

The Oxford team urged the National Institute for Health and Care Excellence, the body that sets prescription criteria for NHS doctors, to review its guidelines in light of the new evidence.

Prof Richard Peto said: “We don’t want to be unduly alarming, but we don’t want to be unduly reassuring.”

The study also found the added risk of breast cancer doubled for women using HRT for 10 years compared with five. Those on treatment for less than a year appeared to suffer no extra risk.

The Royal College of GPS urged patients “not to panic”. Prof Martin Marshall said that while the link was known, “it is a complex relationship”.

He urged doctors to take a “holistic approach to prescribing, considering all the different factors” – adding that GPS were “highly trained” to do precisely that.