Women undergoing hormone replacement therapy (HRT) are 2.7 times more likely to develop breast cancer than those who are not, a new study has found.
Those taking combined HRT, which combats the effects of the menopause, are more likely to develop the disease, with risk increasing the longer it is used, the study says.
The research, published in the British Journal of Cancer, found that those taking oestrogen plus progestogen HRT were 2.74 times more likely to develop breast cancer. Those who had been using the combined HRT for 15 or more years had a 3.27 times increased risk.
The findings have prompted qualifying advice from Irish medical professionals who say the risk of breast cancer can be offset by other lifestyle habits while those currently undergoing HRT should not be unduly alarmed.
Responding to the study, the Irish College of General Practitioners (ICGP) yesterday said all women currently undergoing HRT would have been informed of the additional risk of breast cancer uncovered by previous research.
“[THEY] would have considered their individual risks and benefits before starting on the treatment,” said Dr Miriam Daly, director of women’s health.
“This study suggests a slightly higher risk with combined HRT than previously reported but that risk is still very small.”
Ms Daly said anyone with concerns following from the published research should contact their GP and not cease therapy.
Dr Shirley McQuade of the Dublin Well Woman Centre said a broader view of lifestyle factors and general health was important when weighing up risk levels.
“If women are healthy, not overweight and exercise, these things reduce the risk of breast cancer,” she said.
The highest risk is for women who are overweight, a far bigger threat than HRT. Smoking and alcohol intake are also contributory risk factors.
“There are lots of things that women can do to lessen the risks of breast cancer. [FOR EXAMPLE]if you were to choose between HRT and alcohol,” Ms McQuade said.
“If you went on HRT and stopped drinking you wouldn’t have any increased risk of breast cancer than if you were just drinking.
“The majority of women can manage the menopause with lifestyle changes only. If they have a healthy lifestyle the vast majority will not need HRT. But there are a small number - the estimate is about 10 to 15 per cent - who will have a severe menopausal reaction.”
The study found that once HRT-use ended the increased risk returned to normal levels. Those taking oestrogen-only HRT did not have an increased risk.
HRT is used to treat symptoms of the menopause, such as hot flushes, migraines, disrupted sleep, mood changes and depression, by replacing hormones lost through the menopause.
The results were drawn from the Breast Cancer Now Generations Study which followed more than 100,000 women over 40 years.
Experts analysed data over six years from almost 40,000 menopausal women, 775 of whom developed breast cancer.
For some 10 per cent of women, symptoms can last for up to 12 years. The average age for menopause is 51.
"Our research shows that some previous studies are likely to have underestimated the risk of breast cancer with combined oestrogen-progestogen HRT," said study lead author Anthony Swerdlow, professor of epidemiology at The Institute of Cancer Research in London.
“We found that current use of combined HRT increases the risk of breast cancer by up to threefold, depending on how long HRT has been used.
“Our findings provide further information to allow women to make informed decisions about the potential risks and benefits.”
- Additional reporting PA
