Oestrogen-only HRT 'can reduce breast cancer risk' However, this new study, published in The Lancet Oncology, shows that a less commonly-used type - oestrogen-only - can actually reduce the risk in some women. American researchers examined data from 7,500 women aged 50 to 79 in a trial, who had undergone hysterectomy and had no family history of breast cancer. Half were given oestrogen-only HRT for about six years, and the other half a placebo. However, researchers who followed the volunteers for another six years found those on the HRT were 23 per cent less likely to have developed breast cancer, over 12 years. Garnet Anderson, from the Fred Hutchinson Cancer Research Center in Seattle, said the findings "should provide reassurance about breast safety of oestrogen use for durations of about 5 years for women with a hysterectomy seeking relief from postmenopausal symptoms." Several studies have linked combined HRT (oestrogen and progesterone) with increased rates of breast cancer, although these are increasingly disputed. No studies have definitively found oestrogen-only HRT causes breast cancer, said Dr John Stevenson, an menopause expert at the Royal Brompton Hospital in London. He said about 100,000 women in Britain were now on oestrogen-only HRT, about a quarter of the total.