British Menopause Society
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Fact Sheets: Article

Title: HRT and Breast Cancer

Dr Jenny Williamson, Associate Breast Specialist. January 2006, reviewed January 2008

What causes Breast cancer?

Some cancers are strongly linked to one single causative agent (for example smoking with lung cancer). Breast cancer has no known single cause and multiple factors have been identified which may increase a woman's risk of developing breast cancer in her lifetime.

These include - excess body weight when over the age of 50 years, never having had a baby, having your first baby over the age of 35 years, not breast feeding, the use of the combined oral contraceptive pill within the past 10years and regular increased alcohol intake. Having a mother or sister who has suffered breast cancer under the age of 50 can also increase your risk.

Studies on the use of HRT after the age of 50 suggest there is a small increased risk in breast cancer with the length of time it is used. Other studies would suggest that this risk is only associated with some HRT regimens and not with all forms of HRT. Having a risk factor does not mean that a woman will develop breast cancer and even if a risk factor is identified in a woman with breast cancer there is no way of proving that this was the cause.

Why should I take HRT?

Most women enter the menopause in their late 40's or early 50's when previously regular monthly bleeds become infrequent and stop. Around this time, the majority can expect to experience menopausal symptoms of hot flushes, night sweats, vaginal dryness and mood

changes. These symptoms will be transient in a few women, but many will find them disruptive to their every day life for up to 5 years. A small number of women find that their symptoms remain severe for many years.

Clinical studies have proved that HRT is effective for the relief of these symptoms. There is also good evidence that HRT use defers the loss of bone density.

The benefits of taking HRT for symptom relief during the menopause outweigh the risks associated with its use in most women.

What type of HRT would I need?

If you are having menopausal symptoms and are still having menstrual bleeds, then you will be suitable for sequential combined HRT (that means estrogen daily with the addition of progestogens for 10 or 12 days each 28 day cycle) This method usually gives you a monthly bleed.

If you have stopped having periods for at least 12 months then you can have continuous combined HRT (estrogen and progestogen together daily). This method does not reinstate your monthly bleeds although a few episodes of spotting or light bleeding are common in the early months of use. A drug called Tibolone is another method used to treat symptoms in the same way without causing return of monthly bleeds.

If you have had a hysterectomy (womb removed) then you will only need estrogen.

What is the risk of getting Breast Cancer if I take HRT?

Scientific evidence would suggest that the small increase in the risk of developing breast cancer with HRT differs depending on the type of HRT used. Combined HRT (estrogen + progestogen) probably accounts for 3 extra cases in every 1000 women who use it for 5 years between the ages of 50 – 59 years. There appears to be no increase in the risk for shorter term use of less than 3 years. The use of estrogen only has a lower risk than combined HRT. The risk with tibolone appears to be similar to that of estrogen only.

For how long should I take HRT?

This is not an easy question to answer and must be made on an individual basis as some women experience symptoms life long. It is recommended that if you take HRT for symptom relief, then continuation of this should be reviewed at regular intervals.

If you have had a premature menopause for any reason, and have used HRT for several years up to the age of 50, then you can be reassured and only need to start to count your risk when you continue HRT beyond 50 years of age.

If you start HRT at around 50 years of age then it would be reasonable to consider whether you still need it after 3-5 years. Reducing the dose may help you to identify whether you have any recurrence of symptoms. As yet there is no evidence that smaller doses are safer, but it seems that the older women become, the less estrogen they need for symptom relief and other benefits.

What happens if I stop HRT?

The risk of developing breast cancer associated with taking HRT diminishes when you stop and is no longer evident after 5 years. You must remember that a background population risk will still remain and you should continue with attendance for mammographic screening when requested.

Useful addresses /websites:

The British Menopause Society
is a registered charity dedicated to increasing awareness of post-menopausal healthcare issues
(this site)

NHS cancer Screening Programme

Women's Health Concern advice and up to date information on women's health issues Advice line Tel 0845 1232319

Menopause Matters
accurate information about the menopause and its treatment options

Whilst great care has been taken to ensure the accuracy of information contained in the fact sheets, the authors and the BMS cannot accept any responsibility for any errors omissions, mis-statements or mistakes or for any loss or damage arising from actions or decisions based on information contained in this publication. Ultimate responsibility for the treatment of patients and interpretation of published material lies with the medical practitioner. The opinions expressed are those of the authors, not necessarily those of the BMS. The inclusion in the publication of material relating to a particular product, method or technique does not amount to an endorsement of its value or quality, or of claims made by its manufacturer.
Margaret Rees and Sally Hope January 2008

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