New data halts largest HRT trial
15:35 09 July 02
Original story at newscientist.com.
The largest ever clinical trial of hormone replacement therapy for healthy post-menopausal women has been halted early because the latest data show clearly that the risks outweigh the benefits.
Over 16,000 US women were participating in the trial of a combined oestrogen and progestin treatment, which was due to end in 2008. But increased risks of invasive breast cancer and strokes led researchers to end the study. About 38 per cent of post-menopausal women in the US take HRT.
The findings, released on Tuesday by the Journal of the American Medical Association, are disquieting, according to an editorial in the publication. The authors even go so far as to recommend "that clinicians stop prescribing this combination for long-term use".
But doctors point out that the absolute risk of HRT to an individual woman remains small. For example, the study shows that the increased risk means that in 10,000 women taking HRT for a year, there will be eight more invasive breast cancers, eight more strokes and seven more coronary heart disease events.
David Ontjes, one of the study's investigators from the University of North Carolina School of Medicine, says: "I don't think women taking HRT should panic and stop," although they should discuss the findings with their physician.
He adds that, while it is now clear that the long-term benefits of HRT do not outweigh the risks in healthy post-menopausal women, women who have undergone a hysterectomy and are taking oestrogen alone may indeed benefit from the regimen.
In fact, another arm of the study is still ongoing and the increased risks have yet to surface. "The story is not complete," he says. "This is not the death of HRT."
Traditionally, HRT has been used to ameliorate the unpleasant symptoms of menopause, like hot flushes and vaginal dryness. But taking the hormones for the years after the onset of menopause has also been thought protect women from a host of chronic conditions, such as osteoporosis, heart disease and some kinds of cancer.
Forty centres nationwide were participating in the Women's Health Initiative (WHI), the most comprehensive study to date on the effects of HRT. The women were either given the hormone combination or a placebo.
But the latest findings confirm that HRT results in an increase in the risk of invasive breast cancer when taken for more than three years, a suspicion already voiced in several smaller studies. Furthermore, HRT led to an increased risk of stroke and pulmonary embolism, although the risk of colorectal cancer and hip fracture did decrease.
The data also show that long-term HRT does not protect women from heart disease, and instead increases its chances - a conclusion also reached by a separate study a week ago.
Journal reference: The Journal of the American Medical Association (vol 228, p321)