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In the follow-up involving more than 27 000 women, researchers analysed 13 years of data, including up to eight years of information on what happened after women stopped taking replacement hormones – oestrogen alone or with progestin. The researchers present the most detailed information yet on hormones' health effects by age, and include new information on risks based on time since menopause.
Oestrogen pills, used by women who've had a hysterectomy, appeared to be safer, especially for younger women – those who started taking hormones in their 50s, the study found. That's mainly because of a persistent breast cancer risk among women who'd taken the combined oestrogen-progestin pills. Also, heart attacks risks were strongest among women given combined pills when they were in their 70s and decades past menopause – although in the real world, most hormone users start taking them at younger ages, when risks are lower.
Risks outweigh benefits
For both types of pills, "risks will still outweigh benefits for women who are at older ages," even if they have persistent hot flashes and other menopause symptoms , said lead author Dr JoAnn Manson, preventive medicine chief at Harvard's Brigham and Women's Hospital.
For women in early menopause, the quality of life benefits likely outweigh the risks, she said.
Hormones were once thought to help prevent a variety of age-related ills and many women considered them a staple for retaining their youth. The research was launched in the 1990s to examine some of those beliefs, and the new results confirm that hormones should not be used for disease prevention.
Participants took oestrogen-only pills for about seven years, oestrogen-progestin pills for about five years or dummy pills. The government stopped both studies, in 2002 and 2004, after more health problems were found among hormone users than those assigned to take dummy pills.
The new study includes follow-up through 2010, and some results confirm findings seen earlier. The study appears in the Journal of the American Medical Association.
"It's helpful to have the further analysis. It reaffirms what we've actually been practicing for a while," said Dr Elizabeth Ross, a heart specialist at the MedStar Heart Institute in Washington, DC.
But she noted that the study didn't examine other forms of menopause hormones, including patches and creams, and added, "I don't think the door is closed on our understanding of hormone replacement."
Besides increased risks for breast cancer, and heart attacks mostly among older women, results for oestrogen-progestin users include:
- Risks for strokes and blood clots found during treatment faded but did not completely disappear.
- Hormone users had fewer cases of uterine cancer, a benefit not seen during the treatment phase.
- Fewer hip fractures occurred among hormone users, though this benefit was less robust than during treatment.
Results for oestrogen-only users, compared to dummy pills:
- Fewer breast cancers were found, a result also seen in an earlier follow-up.
- No increased heart attack risks were seen, even among the oldest women.
- Risks for strokes and blood clots disappeared after stopping the pills.
- A reduction in hip fractures seen in the treatment phase faded.
