A review of four major studies into the
effects of HRT found that women who took the treatment for five years had a
higher risk of breast cancer, stroke and blood clots in the lung but were less
likely to suffer from bowel cancer or hip fractures.
Overall, the analysis showed that a woman is more likely to contract a
life-threatening disease when on HRT than to be protected against one.
"The four major trials that have been done, although in different settings
and with different combinations (of HRT), really show consistent results,"
Professor Valerie Beral, of Britain's Cancer Research UK charity, told Reuters.
Millions of women who use HRT to relieve hot flushes and mood swings or to
prevent osteoporosis were caught off guard in July after an American trial
showed HRT raises the risk of stroke, breast cancer and blood clots.
Shares in HRT manufacturers like US-based Wyeth and Germany's Schering
tumbled in the wake of the US trial news in July.
US FINDINGS BACKED
Beral said her analysis of four trials involving 20,000 postmenopausal women,
which is published in The Lancet medical journal, confirm the findings of the US
study.
"They basically support the Women's Health Initiative study," Beral said,
referring to the US trial of women taking combined estrogen and progestogen HRT.
Three of the trials in the analysis studied the effects of combined HRT and
one involved estrogen only.
"Putting all the data together, the results look very similar," said Beral.
"What there is suggests there is no difference between the different types of
HRT preparations."
For women in their 50s taking HRT for five years, the greatest risk is for
developing breast cancer. Women in their 60s have a higher chance of suffering a
stroke or pulmonary embolism, or blood clots in the lungs.
"These result estimates provide a rough guide to the likely overall change in
incidence of these conditions over a five-year period for typically healthy
women in Western countries who use HRT," said Beral.
The review estimates that for healthy women on HRT for five years there would
be a total of six extra cases of either breast cancer, stroke or clot on the
lung among every 1,000 HRT users between aged 50-59.
The number would double to 12 for HRT users aged 60-69.
By contrast, there would be an estimated 1.7 fewer cases of bowel cancer or
hip fracture per 1,000 HRT users aged 50-59 and 5.5 per 1,000 users between
60-69.
The review found no significant change in the risks of endometrial cancer or
coronary heart disease.
Women on the treatment for longer would have an increase in risk that
accumulates with time, said Beral
"We've tried to provide risk estimates for women that they can relate to in
making a decision about whether they want to take HRT or not," she added.
