A second trial looking into the long term effects of hormone replacement therapy (HRT) has been stopped early.
The UK Medical Research Council (MRC) announced last week that a decision had been taken to halt the women's international study of long duration oestrogen after menopause (WISDOM) for “scientific and practical reasons.” The trial, which has cost £10m ($15.5m; €15.9m), was due to be completed in 2016.
WISDOM was investigating the long term effects of oestrogen combined with progestogen and of oestrogen alone on the incidence of, among other diseases, cardiovascular disease, breast cancer, dementia, and osteoporosis.
In July one part of the US women's health initiative (WHI) study, a similar trial involving more than 16000 women, was stopped early after a small increased risk of breast cancer, cardiovascular disease, blood clots, and stroke was found among the women taking the combined form of HRT.
The WHI's data and safety monitoring board concluded that these risks outweighed the decreased rates of osteoporotic fractures and bowel cancers. But the other part of the WHI study, comparing the effects of oestrogen alone with placebo in women who have had a hysterectomy, is still ongoing.
After publication of these initial results the MRC set up an independent international committee to decide on WISDOM's future, although the trial's steering committee had wanted it to continue because important questions about the risk-benefit ratio of HRT remained unanswered.
The international committee's report to the MRC on 16October agreed that some important questions about HRT are still unanswered. But it did not think that the WISDOM trial would substantially resolve them, especially as one of its chief concerns—a large reduction in the risk of coronary heart disease—was no longer likely.
WISDOM aimed to include 16000 postmenopausal women from the United Kingdom plus 6000 from Australia and New Zealand, but it had recruited only 5700 women with the relevant criteria since 1999.
Ray Fitzpatrick, professor of public health and primary care and director of the Institute of Health Sciences at the University of Oxford, chaired the international committee.
In a statement issued by the MRC, he said: “The IIC [independent international committee] was concerned by the slow progress of WISDOM and considered that the results of the trial, which would not be available for another decade, would be unlikely to influence clinical practice.”
Committee member, Philip Hannaford, professor of primary care at the University of Aberdeen, said that further trials looking at the timing and type of HRT would pose logistical difficulties because of the numbers of women required.