It's Your Health
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For many years, women have been prescribed Estrogen with or without Progestin Hormone Replacement Therapy (HRT) to relieve some of the symptoms of menopause. However, recent scientific studies have identified significant risks associated with this therapy.
HRT products have been approved by Health Canada to treat menopausal symptoms such as hot flashes, night sweats, vaginal dryness and in some cases, to prevent osteoporosis. While there are other forms of hormone replacement available, such as the patch, gel and vaginal ring, HRT is most commonly taken in pill form, of which there are two main types:
Progestin is added for the prevention of uterine cancer in women who have not had a hysterectomy (surgical removal of the uterus).
Some earlier studies suggested that the use of HRT products might help to prevent heart disease in post-menopausal women. But the lower incidence of heart disease among these women is now believed to be due to other factors such as diet and lifestyle. The labelling materials approved by Health Canada for HRT products clearly state that they have not been approved for the prevention of heart attack, stroke or any other cardiovascular disorder.
In 1991, the U.S. National Institutes of Health (NIH) launched the Women's Health Initiative (WHI), a set of studies involving healthy post-menopausal women that was carried out in 40 U.S. centres. The WHI included a clinical trial to evaluate the risks and benefits of the two types of HRT (administered in pill form) and to see how they affected the incidence of heart disease, breast cancer, colorectal cancer and fractures in post-menopausal women. The trial was divided into two arms:
In July 2002, after an average 5.2 years of regular follow-up, the NIH prematurely ended the combined (estrogen and progestin) HRT arm of the WHI trial. An independent monitoring board, which regularly reviewed the findings, concluded that there were more risks than benefits among the group using combined HRT, compared with the placebo group. The study found that changes in the incidence of disease per 10,000 women on combined HRT in one year were:
While these numbers appear to be low, they are highly significant. Given that millions of women are taking combined HRT, the number affected over many years is an important public health issue.
Since July, 2002, further results from the Women's Health Initiative trial have been published. Among the findings:
In light of these results, combined estrogen and progestin are not recommended for long-term use in post-menopausal women, except in limited circumstances where other therapeutic choices are found inadequate. The risks of breast cancer, blood clots, stroke, coronary heart disease and dementia (in women aged 65 and over) are considered to outweigh the benefits of fracture reduction and the reduced risk of colorectal cancer, when long term use of HRT is considered.
In March 2004, the estrogen-only arm HRT was discontinued. After nearly seven years of follow-up, NIH reported that estrogen therapy:
In the sub-study of women 65 years of age and older, estrogen was reported to show trend toward increased risk of probable dementia and mild cognitive impairment. This information will be updated as more data becomes available.
Please note that other dosage levels of HRT (Estrogen with or without Progestin) and other forms, such as the patch, gel or vaginal ring, were not examined in this study.
The decision to use HRT should be based on your particular needs and health, and made after a careful medical evaluation. If you are taking or considering taking HRT, you should:
Health Canada is continuing to monitor the benefits and risks associated with HRT, through pre-market reviews and post-market surveillance. Doctors and consumers will be updated on new findings as they are reported. Health Canada is also updating a comprehensive document on menopause. This publication will be posted on the Health Canada Web site as soon as it is available.
For more information on menopause and HRT, contact:
For more information on the NIH study, contact:
Menopausal Hormone Therapy Information Women's Health Initiative Hormone Therapy Study
For more information on Breast Cancer see the It's Your Health article.
For additional articles on this subject and other issues go to the It's Your Health Web site. You can also call (613) 957-2991.
ę Her Majesty the Queen in Right of Canada,
represented by the Minister of Health, 2004
Updated: May 2004
Original: January 2003