10 October 2012

Study stokes new debate over cancer risk

Women who start hormone replacement therapy (HRT) soon after menopause do not show higher cancer incidence within 16 years.


Women who start hormone replacement therapy (HRT) soon after menopause do not show higher cancer incidence within 16 years, according to a Danish study that fuels scientific discord over the treatment's safety.

Indeed, women who took HRT in the investigation had a significantly lower risk of dying or developing heart problems, the researchers wrote in a paper published on the medical website

The new study was hailed by a menopause awareness group but a researcher who led a wider probe into HRT said it was worryingly underpowered.

The HRT/cancer controversy

HRT has been shrouded in controversy since a Women's Health Initiative (WHI) study in 2002 reported a higher risk of breast cancer for women who take it, a finding echoed by the Million Women Study (MWS) a year later.

"We found a significantly decreased risk of death, heart failure or myocardial infarction (heart attack) when hormone replacement therapy was started early in postmenopause," wrote the Danish team.

"This finding was not associated with an increased risk of cancer, stroke, deep vein thrombosis, or pulmonary embolism."

The MWS stirred up a storm when it claimed HRT boosted cancer risk by between 30 and 100%, a finding criticised by other scientists who claimed the study method was flawed.

HRT uses the female hormones oestrogen or progesterone, sometimes combined, to ease menopausal symptoms such as hot flushes, loss of sex drive and vaginal dryness.

Study of great importance

The new study looked at 1 006 recently postmenopausal women, of whom 502 were given HRT and 504 no treatment.

Apart from the HRT group being 5.7 months older, there were no other significant differences between the groups in things like weight, health or smoking habits.

Ten years into the study, in 2002, the women were encouraged to stop using HRT after early warnings of adverse effects from other scientists. Data was taken at this point, and the women followed for another six years.

Analysis of the data after 16 years showed that 27 of the women on treatment had died, three had suffered heart failure and five heart attacks.

In the untreated group, 40 had died, eight had been diagnosed with heart failure and 11 suffered heart attacks. Rates of stroke and cancer did not significantly differ between the groups, wrote the team whose members hail from five Danish hospitals.

They did point out though, that a longer follow-up may be necessary for more definite conclusions on cancer risk. The report underscored several differences with the WHI study.

The mean age of the Danish trial group was 50 compared to 64 for the WHI, and its members started HRT within a year of menopause, compared to 10 years.

The two studies also used different drug types.

What the findings mean

The head of the International Menopause Society, Tobie de Villiers, said the study was "of great importance, as it reflects what happens in real life where women start taking HRT at the time of the menopause."

"In this study HRT did not cause any major harm, and indeed resulted in significant benefits," he said in a statement.

But Francoise Clavel-Chapelon, author of a French study, E3N, which has been following 100,000 women in similar research since 1990, was strongly critical, saying the Danish research was "weak."

Published in 2007, E3N showed that women taking the same drugs the Danish used had "more than double the risk of breast cancer," she said.

(Sapa, October 2012)

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