Women undergoing HRT face increased risk of getting cancer
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It was once described as the last frontier in the emancipation of women, a pill that would ease the transition through the menopause and allow those who took it to slip into a contented middle age. Now the world’s largest study of hormone replacement therapy (HRT) has shown that it may have caused 1,000 deaths from ovarian cancer between 1991 and 2005.
The new finding strengthens the evidence that HRT poses a serious danger to women. Previous results from the same study have shown that the risk of breast cancer and endometrial cancer (of the lining of the womb) is also increased by the treatment.
Overall, the incidence of these three common cancers are increased by 63 per cent among women currently taking HRT compared with those who have never taken it. That means 12 extra cases of cancer for every 1,000 women taking HRT over five years. The risk increases from 19 expected cases among women who had never taken the treatment to 31 among HRT users.
An estimated two million women were taking HRT at the height of its popularity in 2002 in the UK and millions more worldwide. The huge numbers exposed to the drug mean that tens of thousands will have developed cancer as a result.
On top of the cancer risk, HRT also increases the risk of stroke and thrombosis (blood clots). Earlier evidence suggesting it cut the risk of heart disease has not been borne out by later studies. Professor Valerie Beral, chief author of the ovarian cancer study, published in The Lancet, said the argument about HRT was now settled. “In terms of the major health impact of HRT, the adverse effects outweigh the benefits. I don’t think in the serious scientific literature there is any longer a debate about this.”
Referring to a recent study published earlier this month in the Journal of the American Medical Association (Jama), which was claimed to show that HRT may protect some women against heart problems, Professor Beral said it had been misinterpreted.
The study focused on the link between HRT and age and showed that the risks are lower for women who start HRT while still relatively young than for those who take it 20 or more years past the menopause.
But Professor Beral, of the Cancer Research UK Epidemiology Unit in Oxford, said it was wrong to suggest that this showed HRT was safe for younger women. “There is a possible trend of increasing risk with age - though it is opposite for stroke where the risk is higher in younger women. But there is not a significant benefit for younger women. The Jama study concluded that still, on balance, the risks outweigh the benefits.”
In the 1990s, HRT was presented as a panacea for fiftysomething women, offering release from the mood swings, hot flushes and declining libido associated with the menopause.
In 2002, an American trial of 16,000 women, half of whom were on HRT, was stopped three years early after researchers found a sharply increased risk of breast cancer, heart problems and stroke in women on the treatment.
The following year in the UK, the Million Women study led by Professor Beral and largely funded by Cancer Research UK which studied one million British women, a quarter of the female population aged 50-64, from 1996 to 2001, found the risk of breast cancer was doubled among those on HRT. It concluded the therapy had caused 20,000 extra cases of breast cancer over the previous decade.
Use of HRT slumped on both sides of the Atlantic as regulatory agencies moved rapidly to revise their advice. Shares in pharmaceutical manufacturers of the products nosedived.
In Britain the numbers using HRT halved, but there are still an estimated one million women taking it today. The risks associated with the treatment relate to current users and are thought to return to normal once the drug is stopped.
Professor Sean Kehoe, consultant gynaecologist at John Radcliffe Hospital, Oxford, and spokesperson for the charity Wellbeing of Women, said: “The use of HRT for five years means one extra woman would develop ovarian cancer out of 2,500 using HRT compared with those not using HRT. Therefore this increase in a rare disease needs to be balanced against the potential effects on the woman’s quality of life when ceasing HRT.”
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