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Oestrogen therapy, breast cancer and the menopause

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Questions over hormone therapy and its role in breast cancer risk hit the spotlight again last week, after conflicting opinions on the issue were published following new results from the large, US Government-funded Women’s Health Initiative (WHI) trial programme.

In 2004, the WHI found that human replacement therapy (HRT) given during or after menopause did not, as expected, cut a woman’s risk of heart disease, but did increase risk of stroke. Now, seven-year follow-up data from the WHI, carried out at the Fred Hutchinson Cancer Centre in Seattle, US, has found that for women with a prior hysterectomy, oestrogen-only HRT is less risky for women in their 50s than was previously thought, and may protect against breast cancer.

For women in their 70s, however, oestrogen-only HRT increased the risk of colorectal cancer, chronic disease, and death, according to the new results from the WHI. The WHI Oestrogen-Alone Trial is a double-blind, placebo-controlled, randomised clinical trial evaluating the effects of conjugated equine oestrogens (CEE) on chronic disease incidence among postmenopausal women with prior hysterectomy. The trial intervention was stopped one year early, after a mean of 7.1 years of follow-up, because of an increased risk of stroke and little likelihood of altering the balance of risk to benefit by the planned termination date, according to the authors.

Summing up the results in JAMA, the authors wrote: “Oestrogen-only therapy, currently used in women with menopausal symptoms who have had a hysterectomy, may decrease breast cancer risk if it is used for fewer than five years. We found that this benefit persisted even after the hormone therapy was discontinued.” The researchers found that the negative effects of hormone therapy, primarily stroke, went away after the women stopped treatment. The benefits, mainly a decreased risk of bone fracture, also disappeared. However, other specialists have cautioned against oestrogen-only therapy in women who have had a hysterectomy, despite the WHI results.

An editorial in the same JAMA issue points to the long-standing evidence that oestrogen-only therapy raises the risk of breast cancer. Commenting on the issue to IMN, co-author of the JAMA editorial Dr Graham Colditz, Niess-Gain Professor of Surgery at Washington University School of Medicine in St Louis, US, said that while short-term use of oestrogenonly therapy appears safe, the longterm consequences of that short use are unknown. The editorial cautions doctors to look at the “larger body of evidence that contradicts this new finding” and shows that hormone therapy may raise the risk of breast cancer. “While oestrogen therapy is commonly used on a short-term basis to manage menopausal symptoms after hysterectomy, questions remain about its safety, including whether there is a safe duration of use,” said Dr Colditz.

The Women’s Health Initiative (WHI) began recruiting participants in 1993 to look at the entire risks and benefits of hormone therapy, including oestrogenonly therapy, when used to prevent chronic disease. In the early 1990s, pointed out Dr Colditz, not only was hormone therapy standard practice in treating women with menopausal symptoms, it was thought to be beneficial for preventing age-related diseases including heart disease and breast and colorectal cancers. “Back then hormone therapy was prescribed almost like a vitamin,” he said.

In the editorial, Dr Colditz and his colleague Dr Emily Jungheim, assistant professor of obstetrics and gynaecology at the Washington University School of Medicine, question whether the WHI was an appropriate population to study when asking whether oestrogenonly therapy is safe for treating the symptoms of menopause. “Generally, the women in the WHI do not represent the typical woman who might be prescribed hormone therapy for menopausal symptoms today. For example, 68 per cent of the women in the WHI were over age 60 when enrolled in the study, making them older than the average woman entering menopause,” they wrote. “And though the women were followed for 10 years after therapy stopped, the average amount of time they actively took hormones was only three and a half years. Therefore, the WHI results cannot address the risks and benefits of longer-term oestrogen use.”

They did admit that there is still a role for short-term hormone therapy in treating women with severe menopausal symptoms, especially those experiencing premature menopause. “The symptoms women experience around the time of menopause can be significant. There may be a role for hormone therapy for some women who cannot find relief from other things,” Dr Colditz told IMN. “But it’s worth exploring other options including medications and lifestyle changes. I believe it is hard to inform patients based on this data,” he said. However, the authors of the WCI trial obviously disagree. Last week, study co-author Dr Andrea LaCroix, PhD, from the Fred Hutchinson Cancer Centre, said: “Our findings… do not mean that women should take oestrogen to prevent breast cancer. But they do suggest that some younger postmenopausal women – those with a prior hysterectomy – may take oestrogen for up to six years without significant risk…. Now women and their doctors have more information than ever before on deciding whether to start oestrogen and when to stop it.” I

n the study, the authors noted that there will most likely never be largescale clinical trials of modern forms of HRT. “All we can say today is that the best evidence on HRT comes from this large trial,” said Dr LaCroix. While the specialists disagree strongly about the relevance of the WHI findings, they do agree that doctors should speak to women facing severe menopausal symptoms about every option before rushing into treatment.

 

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