The rates of disease were not large, but considering that 40 per cent of North American women over the age of 50 use HRT, health officials decided to stop giving combined estrogen-progestin HRT to women in the trial and warn the public.

She and other NIH researchers are working to tease out of the WHI data whether certain characteristics make women more prone to hormone dangers, how the therapy affected their quality of life, and the impact of stopping HRT.

Other studies involving HRT are continuing. Researchers are studying whether estrogen use by women who have had hysterectomies is safe and whether hormones prevent dementia.