Questions about HRT

What is menopause and what are the common symptoms?

Why do women take HRT?

Does HRT cause breast cancer?

How does HRT affect my risk for other diseases?

What is the controversy about HRT and heart disease?

How do the risks for taking HRT compare with other risk factors?

What's the evidence? What do we know about HRT?

Australian Drug Evaluation Committee recommendations

What is "risk"?

Should I stop taking HRT?

How quickly will my risk fall if I stop taking HRT?

What is menopause and what are the common symptoms?

Menopause is the time when a woman stops having periods, sometimes referred to as the "change of life". Many women experience changes in their body, or symptoms of menopause.

Some women experience minor discomfort or are not bothered by symptoms at all, but for other women symptoms may be troubling.

Hot flushes are the most common troubling symptom, with one in four women experiencing severe or frequent hot flushes. Other symptoms that some women experience include unpredictable menstrual periods (sometimes light or irregular, sometimes heavy and prolonged); disturbed sleep; a dry vagina, making sex uncomfortable; less desire for sex (loss of libido); more frequent and urgent need to pass urine; joint and muscle pain; headaches, migraine; uncharacteristic tiredness, anxiety or irritability; and depression or mood swings.

Few women have all these symptoms, and they don't occur all at once. Some women notice symptoms for only a few months, but for others they may last for years.

HRT has been proven to work very well in controlling hot flushes, night sweats and some other menopausal symptoms.

Why do women take HRT?

Women take hormone replacement therapy (HRT) for a variety of reasons. In recent years HRT has been prescribed by doctors to help relieve symptoms due to menopause (change of life) or to reduce risk of hip fracture or heart disease, both of which increase after menopause. If you are presently taking HRT, you should talk to your doctor about why he or she suggested you take it, and whether - or for how long - you should continue to do so.

It is wise to have an annual review of your HRT with your doctor, so that the type and dose and the latest recommendations based on any new evidence about its use can be reviewed. It is also important that your doctor is aware of your own or your family's medical history, for example if members of your family have breast cancer or another cancer, or heart disease.

For some women there may be good reasons to take HRT for short periods. However, it's important to talk to your doctor to ensure that HRT is recommended for you.

Does HRT cause breast cancer?

In Australia, one in 11 women will be diagnosed with breast cancer before the age of 75.

Two recent large studies have found that women who take HRT for five years or longer have an increased risk of breast cancer. See What's the evidence for more information about these studies.

While combined HRT (oestrogen plus progestogen) will increase your chances of getting breast cancer, only a small proportion of women who take HRT will get breast cancer because of it. Even among women who have taken HRT for five years the vast majority will not get breast cancer in that period and very few will get it because of HRT.

  • In 10,000 women who have had menopause and do not use HRT, about 30 will get breast cancer.
  • If the same 10,000 women did use HRT, 38 women (ie 8 more) would get breast cancer.

To see the increased risk of getting breast cancer because of HRT for women in your age group, click here.

There are other factors that also cause an increase in breast cancer, for example being overweight or having a family history of breast cancer. If you are concerned about your risk of breast cancer you should discuss this with your doctor. If you are considering stopping HRT you should discuss this with your doctor too.

For women who have had breast cancer before, the recent HABITS study found that the use of HRT increases the risk of a new breast cancer developing.

Whether you use HRT or not, regular breast screening is recommended for all women aged 50 and over.

How does HRT affect my risk for other diseases?

Trials investigating the effects of long-term use of combined HRT (oestrogen plus progestogen) have found that risks for several diseases are increased.

The potential risks from long-term use of HRT include increases in heart disease, breast cancer and vein thrombosis (blood clotting) leading to an increased risk of stroke.

It was previously thought that HRT would prevent health problems such as heart disease, stroke and dementia, but recent evidence indicates this is probably not true.

Evidence suggests HRT use reduces the risk of fractures and bowel cancer.

The National Health and Medical Research Council (NHMRC) has conducted a comprehensive review of the literature on the effects of HRT. (See Links.)

What is the controversy about HRT and heart disease?

Since the release of the US Women's Health Initiative study results in 2001, there has been considerable controversy in the news media about the use of HRT.

Before the release of the Women's Health Initiative results it was generally thought that HRT gave women protection from heart disease, that is, that HRT prevented heart disease. The Women's Health Initiative was the first major study to cast doubt on this belief, thus it was bound to be controversial. The controversy remains because some researchers believe that the Women's Health Initiative study was unable to detect the protective effects of HRT taken during menopause against heart disease because the average age of women participating in the study was 63 years (ie most were already post-menopausal when they started taking HRT) .

It is important to remember that the controversy relates only to the effect of HRT on heart disease. There is no debate about the effect of HRT on breast cancer, or the other effects of HRT (see How certain are we?).

Further research is required to determine if HRT taken during the menopause is protective against heart disease. Until this question is answered care needs to be taken when using the information on heart disease to decide whether to take, or stop taking, HRT. At this time HRT should not be used just for preventing or treating heart disease.

How do the risks for taking HRT compare with other risk factors?

Your risk of getting breast cancer increases with age, whether you use HRT or not.

Being overweight or very overweight is a risk factor for both breast cancer and heart disease. An American Cancer Society study (February 2004) suggested that the more weight a woman gains during her adult years, the higher her breast cancer risk. Weight gain could increase breast cancer risk as much as HRT does.

To help in understanding how HRT affects your risk you can compare the risks caused by taking HRT with those caused by being overweight or very overweight.

What's the evidence? What do we know about HRT?

The US Women's Health Initiative study

The Women's Health Initiative study is a large trial investigating the major health risks and benefits of taking HRT for post-menopausal women aged 50 to 79 years. The research group released some findings in July 2002, and further results in 2003.

The study was aimed at assessing the expected benefits of HRT, such as reducing the risk of hip fractures and bowel cancer, but was stopped early because it was found that women using the combination HRT (oestrogen plus progestogen) had an increased risk of serious health problems.

The study found that: women taking combination HRT had:

  • an increased risk of invasive breast cancer;
  • an increased risk of coronary heart disease (rather than the decrease that was expected);
  • an increased risk of stroke;
  • an increased risk of vein thrombosis and pulmonary embolism (blood clots in the legs and lungs).

There was a reduced risk of hip fractures and bowel cancer.

The 2003 study report confirmed the earlier findings of an increased risk of breast cancer for women using HRT. It also showed that HRT did not reduce the risks of developing dementia or heart disease, as had been previously thought, but in fact slightly increased these risks.

The study's finding that HRT increased women's risks for breast cancer and heart disease was widely reported in the media, causing concern among women taking or thinking about taking HRT. Many women were confused or overly concerned because of the way in which the outcomes were reported. See What is "risk" below.

The Million Women Study (UK)

The Million Women Study involves more than one million British women aged 50 and over and aims to answer questions about the factors affecting women's health, particularly the effects of HRT.

A report of the study published in August 2003 found that women using HRT had an increased risk of breast cancer compared with women who had never used HRT.

This study found that:

  • women who used HRT were at increased risk of breast cancer;
  • the risk increases with duration of use;
  • the risk was greater for women taking combined oestrogen-progestogen therapy compared with oestrogen alone;
  • different HRT products and different ways of taking HRT (tablets, patches, implants) all increase the risk; and
  • stopping HRT reverses the risk over time.

HABITS Study (Hormonal replacement therapy after breast cancer - is it safe?)

The aim of the HABITS study was to investigate whether HRT was safe for women who had had breast cancer previously.

The study was stopped after two years because the researchers found that women (who had previously had breast cancer) using HRT had an "unacceptably high" risk of developing a new breast cancer.

Australian Drug Evaluation Committee recommendations

The Australian Drug Evaluation Committee (ADEC) is a group that provides independent, scientific evidence on drugs to the Australian Government. The committee has reviewed all the recent research findings about HRT use. It now advises women to consider using HRT only to relieve serious hot flushes and for no longer than is necessary to achieve this. The committee has advised that HRT should not be used for the prevention of osteoporosis and is no longer thought to be protective against heart disease.

What is "risk"?

Risk is a person's chance of getting a disease over a certain period of time.
A risk factor is anything that raises or lowers a person's chance of getting a disease. Taking HRT is a risk factor because it raises and lowers the chances of getting certain diseases.

Risk can be expressed in different ways, potentially confusing people about how much a factor increases or decreases a particular risk.

For example, the Women's Health Initiative study found that the risk of breast cancer for women taking combined HRT was 1.26 times higher than that for non-users. This led to reports that breast cancer risk increased by 26 per cent. Many women found this alarming and immediately stopped taking HRT.

But, if the increased risk is explained in absolute terms, it is easier to understand. [The risk of developing breast cancer was 38 per 10000 for women who were long-term users of HRT, compared to a risk of 30 per 10000 for women who had never used HRT.] So, for every 10,000 women taking HRT, there would be 8 more women with breast cancer.

Should I stop taking HRT?

You should talk to your doctor before making a decision about whether to stop taking HRT, and if you do decide to stop you need advice about how to do so slowly, rather than suddenly.

Your personal circumstances - including family history, the type of HRT you are using and menopause symptoms, for example - will affect the risks and the benefits to you of using HRT. Some women choose to use HRT for a short-term, or even longer-term, after weighing the increased risks against the impact of their menopause symptoms.

How quickly will my risk fall if I stop taking HRT?

We know from the Women's Health Initiative and Million Women studies that your extra risk of breast cancer falls as soon as you stop taking HRT. After five years, your risk is the same as if you had not used HRT.

We don't have the same quality of information about heart disease, stroke and vein thrombosis, but it is probable that the extra risks of these diseases also fall quite quickly after stopping HRT.