Study Summary
A significant decline in breast cancer rates amongst Australian women aged over 50 years has been linked to a recent dramatic decrease in the use of hormone replacement therapy (HRT), according to new research by The Cancer Council NSW.
The research, published in Medical Journal Australia , on 2 June 2008 found that the use of HRT in Australia dropped by 40 per cent from 2001 to 2003 following the US Women's Health Initiative study, which highlighted HRT's adverse effects. During the same period, there was a significant seven per cent drop in breast cancer rates among women aged 50 and over, which is equivalent to 600 fewer cases of breast cancer among Australian women.
However, no change in the breast cancer rate was observed in younger women, which is expected because few women under 50 use HRT.
These findings are positive, indicating that the decision of women and their health professionals to limit HRT use has resulted in a substantial reduction of breast cancer.
These results are similar to results found in the USA. In both countries HRT use was very common before its adverse effects became known in 2002, after which there was a rapid decrease in its use. The decline in breast cancer does not appear to be explained by any other factors, such as changes in breast cancer screening or use of other medications.
These results are also consistent with other evidence that women can reduce their risk of breast cancer quickly by stopping or reducing use of HRT. So, by reducing their use of HRT, women and their doctors have had a very positive impact on breast cancer in Australia.
The drug regulatory bodies in Australia, USA and Europe are unanimous in recommending that HRT only be used for menopausal symptoms, not the long-term prevention of disease, and that women need to be fully informed about the risks, including the elevated risk of breast cancer.
For more information read Frequently asked questions and answers
Note to GP's: If you haven't received a fax notification
about this study, please contact 13 11 20 for more information.
______________________________________________________
HRT and Breast Cancer
Frequently asked questions and answers
Why did the researchers conduct this study?
Generally, what does this finding mean for women?
What does this finding mean for women experiencing menopausal symptoms?
Should I be worried?
I have been taking combined HRT for five years? Should I stop taking it?
Can you tell me about other medications I can take to help relieve my menopause symptoms?
What would the Cancer Council like to see happen based on these findings?
How can we be sure the changes in breast cancer incidence are due to HRT? Could other things have caused the change, such as breast screening?
The decrease in breast cancer incidence occurred so quickly – how could this be due to HRT?
I've heard that 5 years of HRT doesn't cause a large increase in breast cancer risk. Is there a safe amount of time to use HRT?
Recently I've read HRT is safe, as long as the treatment is tailored to the individual woman's needs.
Why do some women continue to be treated with HRT?
How big is the risk of breast cancer relating to HRT?
How do the risks related to HRT compare with other breast cancer risk factors?
Why did the researchers conduct this study?
- Recent findings from the US showed a large drop in breast cancer incidence following a rapid decline in use of HRT from 2002 onwards.
- The researchers wanted to see if the same thing had happened in Australia.
Generally, what does this finding mean for women?
- This finding is good news for women because it adds to the evidence that women can reduce their risk of breast cancer by stopping HRT use, or using it only for the shortest possible time.
- These findings reinforce the existing guidelines from regulatory agencies in Australia, the USA and Europe (the Therapeutic Goods Administration, the UK's Medicines and Healthcare products Regulatory Agency, and the US Food and Drug Administration) that say that HRT should only be used for menopausal symptoms, not for the prevention of disease.
- If HRT is used for menopausal symptoms, then it should be used for the shortest possible time and women need to be fully informed about the risks.
- The Therapeutic Goods Administration in Australia recommends that women taking HRT have the therapy reviewed every six months to check whether it should be discontinued.
- Breast cancer is a major consideration, but it is not the only consideration, since HRT also increases the risk of stroke, blood clots and ovarian cancer and reduces the risk of fracture.
What does this finding mean for women experiencing menopausal symptoms?
- Women with menopausal symptoms need to make an informed decision about whether or not to use HRT. Some women with severe symptoms may consider running the additional risk of breast cancer, while others may choose to avoid it.
- If HRT is used for menopausal symptoms, then it should be used for the shortest time possible.
- The Therapeutic Goods Administration recommends that women taking HRT have the therapy reviewed every 6 months to check that they really need to be taking it.
Should I be worried?
- No – there's no need to panic. Research is all about arming women with information so they can make informed choices.
- If you have severe menopausal symptoms – you and your doctor can look at the risks associated with the drug and weigh them up with the benefits to you personally.
- The current advice from the Therapeutic Goods Administration is that women on HRT should have the therapy reviewed every six months to check whether continuing therapy is necessary.
I have been taking combined HRT for five years?
Should I stop taking it?
- The Cancer Council NSW cannot advise you about whether you should stop taking combined HRT. You should talk to your doctor. However, evidence suggests that the risk of breast cancer linked with combined HRT declines after treatment is stopped.
Can you tell me about other medications I can take to help relieve my menopause symptoms?
- The Cancer Council NSW can't advise you about other medications for menopausal symptoms. Again, you should talk to your doctor.
What would the Cancer Council like to see happen based on these findings?
- Women and their doctors have done a great job in reducing use of HRT and our findings suggest that this has led to a fantastic reduction in breast cancer.
- However, there are still women out there using HRT for long periods of time and they and their doctors should consider carefully why they are taking it and whether the benefits at that point outweigh the risks.
How can we be sure the changes in breast cancer incidence are due to HRT? Could other things have caused the change, such as breast screening?
- In any study, researchers try and account for other factors that may influence the result. To increase the reliability of the recent study, the researchers ruled out breast cancer screening trends and breast cancer prevention drugs as major contributors to this fall in breast cancer incidence in women over 50.
- It is important to note that there does not appear to have been any dramatic short-term changes to other known risk factors that might explain the drop in breast cancer, such as if many women had dramatically reduced their alcohol consumption or if the obesity rates had suddenly lowered (which has not occurred).
The decrease in breast cancer incidence occurred so quickly – how could this be due to HRT?
- This is a trend noticed worldwide and is consistent with the body of evidence showing that the effects of HRT upon breast cancer risk are rapidly reversible.
- It is not altogether clear why HRT affects breast cancer so rapidly, but we do know that oestrogen increases cell division in the breast and this may increase the likelihood of genetic errors leading to cancer.
I've heard that 5 years of HRT doesn't cause a large increase in breast cancer risk. Is there a safe amount of time to use HRT?
- Overall, the current evidence is that any use of HRT will increase the risk of breast cancer and the longer a woman uses HRT, the greater her increase in risk will be.
- The current guidance is that HRT should only be used for severe menopausal symptoms and should be taken for the shortest time possible and reviewed every 6 months.
Recently I've read HRT is safe, as long as the treatment is tailored to the individual woman's needs.
- Overall, the evidence shows that both combined HRT and oestrogen-only HRT increase the risk of breast cancer; combined HRT to a greater extent than oestrogen-only.
- The study's findings show the importance of HRT use as a risk factor for breast cancer. They indicate that by avoiding HRT, a large number of women have avoided getting breast cancer.
Why do some women continue to be treated with HRT?
- HRT is still a useful medication in women with menopausal symptoms who have been fully informed about the risks and use for a short a period as possible.
- The Therapeutic Goods Administration recommends that for women who choose to take HRT, their need for therapy should be reviewed every six months.
How big is the risk of breast cancer relating to HRT?
- HRT actually has a substantial effect on breast cancer risk, and risk increases the longer a woman takes HRT. A recent review of the evidence by the UK drug regulatory authority found that in the European context after five years of use, women taking oestrogen-only HRT have about a 20 per cent increase in breast cancer risk and women taking combined oestrogen-progestogen HRT have around a 60 per cent increase in risk, compared to women who have never used HRT.
- The same review found that if 1,000 women in their 50s took combined HRT for 5 years then there would be six additional cases of breast cancer, on top of the 10 cases that would usually be seen. Or an extra nine cases among women in their 60s, on top of the 15 cases that would be expected in this age group.
- We all know that breast cancer is common. Before the decrease, there were around 9,000 new cases a year in women over 50 years of age, so any decrease in risk from that level is very important. And that's not considering the additional risks of stroke, blood clots and ovarian cancer found in women using HRT.
- The findings of the recent paper suggest that giving up HRT has caused national breast cancer rates to decline; to do so it would have to have a substantial effect on risk.
How do the risks related to HRT compare with other breast cancer risk factors?
- Avoiding HRT is one of the simplest ways that women can prevent breast cancer and the recent study's findings show that just doing this has had a substantial impact on breast cancer in Australia, with the equivalent of 600 cases prevented each year.
For information and counselling call the Cancer Helpline on 13 11 20 for the cost of a local call .
