Findings from the American Women’s Health Initiative

Professor Henry Burger writes to help us understand some of the latest findings from this large study.

Prof Burger is the Chairman of the Research Committee at the Jean Hailes Foundation for Women’s Health.

Background

The Women’s Health Initiative (WHI) was set up by the USA National Institutes of Health in 1991. Its main aim was to study postmenopausal women and their most common causes of death, disability and problems with their quality of life. At the end of the day, the aim was to reduce heart disease, cancer and osteoporosis.

One part of the Initiative consisted of two hormone treatment trials with the aim of determining whether such treatment would lower heart disease risk and would increase breast cancer risk. One trial used oestrogen plus a progesterone (combined treatment) in women with a uterus, the other used oestrogen alone for women with hysterectomies.

Some very useful findings have come from the study. The combined treatment trial ended early in 2002, after a fear that some women developed breast cancer, possibly from hormone therapy. But we now know that there was no significant increase in breast cancer risk when the trial was ceased after 5.2 years in those women who had never previously used such treatment.

In the oestrogen only trial there were fewer cancers in the hormone treated women.

The information below looks at hormone therapy and whether it helps prevent heart disease.

Several large medical research studies have given us a lot of valuable information – all helping us understand the impact of hormone therapy on women’s heart health.

Timing of hormone therapy

As we look back and study all the findings, there has been a lot of debate about whether the age when a woman takes hormone therapy has an impact on the health of her heart.

We are fairly sure that hormones given to a woman before she has significant damage to her arteries (ie close to the time of menopause) would reduce the risk of heart disease developing. Giving it to a woman who already has developed artery damage (which tends to occur as time from menopause increases), could not and would not protect her from heart disease. The majority of women in the WHI hormone trials were many years from menopause and had multiple heart disease risk factors.

This year, scientists involved in the WHI, have tried to be even clearer. Scientists confirm that women in one study who began hormone therapy near menopause had:

• 34% less risk of heart disease when taking oestrogen alone and
• 28% less risk for combined therapy
• Women who had started hormone therapy more than ten years after menopause were not protected from heart disease.

The scientists looked carefully at the information collected for the WHI and decided there was a greater risk of heart disease in women who started hormone therapy when they were long past menopause.

Timing is crucial

We now know that the timing of hormone therapy is crucial. If hormones are to protect us – or increase our risk of heart disease – doctors need to know when it is appropriate to prescribe, and when not to.

Women need to know there is no evidence that harm will come from taking hormones close to menopause (as is the normal practise for Australian women with symptoms). In fact, hormone therapy appears to protect the hearts of many women. It is only when a woman with a risk of heart disease starts hormone therapy many years later that problems could arise. This was the case for the American women involved in the WHI study.

By far the majority of Australian women who use hormone therapy do so around the time of menopause.

Summary

There is no reason for anxiety about breast cancer or heart disease for women using hormone therapy for three to five years to deal with symptoms around the time of menopause.

Older women who have been using hormone treatment for many years should discuss their treatment with their doctor. In many instances ongoing hormone treatment would be reasonable.

Older women, more than 10 years postmenopause are advised to consider their options carefully before beginning hormone therapy, due to the potential increased risk to the heart.

Content updated March 30, 2006