In 1995 researchers at the Harvard Medical School reported that hormone replacement therapy (HRT) increased the risk of breast cancer in postmenopausal women. The fact that unopposed estrogen therapy increases the risk of breast cancer had been reported in 1992. Shortly thereafter a large clinical trial was begun to see if estrogen/progestin therapy (HRT) would be of benefit to postmenopausal women with heart disease. This trial, the Heart and Estrogen/Progestin Replacement Study (HERS), involved 2763 postmenopausal women with documented coronary heart disease. Half the participants (1380 women) were assigned to receive 0.625 mg of conjugated estrogens plus 2.5 mg of medroxyprogesterone acetate daily; the other half (1382 women) received a placebo. After 4.1 years of follow-up there was no indication that HRT was of any overall benefit in preventing non-fatal heart attacks or death from heart disease. It did appear that HRT users had more cardiac events than the placebo users in the first year, but this was compensated for by fewer events in years three to five. The HERS study was continued in a slightly modified form (HERS II) for another 2.7 years. At the end of the total 6.8 years of follow-up the conclusions were:
There was a slight, but statistically non-significant increase in cancer incidence among HRT users. Breast
cancer rates were 27 per cent higher in the HRT group and lung cancer incidence was 39 per cent higher.
Women who used HRT also tended to have more hip fractures. The researchers conclude that HRT does
not reduce cardiovascular events in women with heart disease and increases the risk of blood clots,
gallstones, and hip fractures.
A larger trial involving 27,348 healthy women on HRT has just concluded that HRT increases the risk of
blood clots, stroke and heart attacks in these women and may increase the risk of breast cancer. NOTE:
This study was funded by Wyeth-Ayerst Research, a pharmaceutical company.
Editor's comment: There has been some hope that HRT may help prevent Alzheimer's disease. A recent study, however, demolished this notion. It is now clear that HRT has no health benefits – quite the contrary – and that there is no medical justification for prescribing it.