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HRT short-term use raises risk of ovarian cancer, warns study

Around 40% higher risk of cancer after just a few years use of HRT

Adrian O'Dowd

Friday, 13 February 2015

Women who take hormone replacement therapy (HRT) for the menopause, even for a few years, are more likely to develop ovarian cancer, according to a detailed re-analysis of all available evidence, published today in The Lancet.

A team of researchers found that short-term use of HRT was associated with increased risk of developing the two most common types of ovarian cancer.

The study*, funded by the Medical Research Council and Cancer Research UK, was a meta-analysis of 52 epidemiological studies, involving a total of 21,488 women with ovarian cancer, almost all from North America, Europe and Australia.

Although use of HRT fell sharply about a decade ago, this decrease has now levelled off and in the UK and USA alone, around 6 million women are still taking HRT.

Existing WHO, US and European HRT guidelines do not mention ovarian cancer, and UK guidelines (currently being revised) state only that ovarian cancer might be increased with long-term use.

The international Collaborative Group on Epidemiological Studies of Ovarian Cancer, organised by the University of Oxford and involving more than 100 researchers worldwide, analysed individual participant data from 52 relevant studies.

They found that there was a significantly increased risk of developing ovarian cancer in current or recent users (i.e. women who had used HRT within the past five years), but although the risk of ovarian cancer fell over time after stopping treatment, women who had used HRT for at least five years still had a somewhat increased risk of ovarian cancer 10 years later.

Women who used HRT for just a few years were 37% more likely to develop ovarian cancer than women who have never taken HRT.

Of the four main types of ovarian cancer, an increase in risk was seen only for the two most common types (serous and endometrioid ovarian cancers).

Study co-author Professor Sir Richard Peto from the University of Oxford, said: “For women who take HRT for 5 years from around age 50, there will be about one extra ovarian cancer for every 1,000 users and one extra ovarian cancer death for every 1,700 users.”

Study co-author Professor Dame Valerie Beral, also from the University of Oxford, added: “The definite risk of ovarian cancer even with less than 5 years of HRT is directly relevant to today’s patterns of use – with most women now taking HRT for only a few years – and has implications for current efforts to revise UK and worldwide guidelines.”

Fiona Osgun, Cancer Research UK's health information officer, said: “Research had already shown an increased risk of ovarian cancer for women using HRT for longer than five years.

“But this new, comprehensive analysis shows there’s also a risk if you use HRT for less time than that. Once a woman stops taking HRT her risk of ovarian cancer can go back down over time.​

“HRT is effective at reducing symptoms of menopause and there are many factors at play in a woman’s decision to use it or not.”

The Medicines and Healthcare Products Regulatory Agency (MHRA) said it would evaluate the findings of the study and its implications for shorter-term use and update product information as necessary.

MHRA vigilance and risk management of medicines (VRMM) division deputy director Dr Sarah Branch said: “Our advice has always been that the lowest effective dose of HRT should be used for the shortest possible time.

“The decision to start, continue or stop HRT should be made jointly by a woman and her doctor, based on the best advice available and her own personal circumstances, including her age, her need for treatment and her medical risk factors.”

* Collaborative Group on Epidemiological Studies of Ovarian Cancer. Menopausal hormone use and ovarian cancer risk: individual participant meta-analysis of 52 epidemiological studies. The Lancet, February 2015. DOI: 10.1016/S0140-6736(14)61687-1

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