No breast risk with oestrogen-only HRT
Oestrogen-only HRT does not increase the risk of breast cancer and could even reduce risk,
new findings from the major Women's Health Initiative trial suggest.
Rates of invasive breast cancer were 20 per cent lower among women on oestrogen-only HRT than those on placebo, although the difference fell short of statistical significance.
Study leader Professor Marcia Stefanick, professor of medicine at Stanford Prevention
Research Center in California, US, concluded: 'Oestrogen-only HRT alone for seven years
does not increase breast cancer incidence in postmenopausal women with hysterectomy, and may decrease the risk of
early stage disease and ductal carcinoma.'
Professor Valerie Beral, who led the Million Women Study, which found a small increased risk of breast cancer with
oestrogen-only HRT and a much bigger risk with combined HRT, said the new results were important.
Professor Beral, Cancer Research UK professor of epidemiology at the University of Oxford, said: 'Our main message was that oestrogen-only carried less risk of cancer than combined. Some of the difference between US and European studies can be explained by obesity so they're not inconsistent.'
Professor Beral said regulatory groups should look at whether oestrogen-only HRT might be safer than combined HRT. 'I don't think regulatory bodies have taken it seriously. It makes sense to me but there are other things worth considering such as cancer of the ovary.'
The study, published in JAMA last week, followed more than 10,000 postmenopausal women with hysterectomy for seven years.