Oestrogen lowers breast cancer risk,says study

The research,part of the landmark Womens Health Initiative study,is likely to surprise women and their doctors,who for years have heard frightening news about the risks of hormone therapy. But most of those fears are related to the use of a combination of two hormones,oestrogen and progestin,which are prescribed to relieve symptoms of menopause,and have been shown to increase a womans risk of breast cancer.

The new findings,reported Tuesday in The Journal of the American Medical Association,come from 10,739 women in the Womens Health Initiative study who had previously had a hysterectomy. While other women in the study were taking combination hormone therapy,women without a uterus took oestrogen alone or placebo for about six years and were followed for 11 years. The oestrogen-only group wasnt given progestin,which is prescribed only to protect the uterus from the harmful effects of oestrogen.

The women with hysterectomies who used oestrogen alone had a 23 per cent lower risk for breast cancer compared with those who had taken a placebo. This is in stark contrast to the higher risk of breast cancer shown in the oestrogen-progestin part of the trial.

Decreased risk of breast cancer in this group is something we didnt expect when we started WHI hormone therapy trials, said Andrea Z LaCroix,the studys lead author.

The data also indicated that for every 10,000 women in their 50s,those using oestrogen would experience 12 fewer heart attacks,13 fewer deaths and 18 fewer adverse events like blood clots in a given year. But,for every 10,000 women in their 70s,using oestrogen would cause 16 extra heart attacks,19 extra deaths and 48 serious adverse events.