Can changing your lifestyle protect you from breast cancer?
Publication Date:04/10/2007
Thousands of cases of breast cancer could be prevented over the next 20 years if women make some changes to their lifestyle, according to new research.
Your risk of getting breast cancer varies depending on lots of different things. Some you can change and some you can't. We look at the evidence, to see how much difference you can make to your risk of breast cancer.
Men get breast cancer too, but it's much less common. In this article we look at what women can do to reduce their risk.
What do we know already?
Across a lifetime (from birth to age 90), a woman's risk of breast cancer is about 1 in 9. That might sound very high, but the risk changes a lot with age. Before 40, the risk is only 1 in 200. By the age of 70, it's 1 in 15.
Breast cancer risk depends partly on your family history and the genes you inherit from your parents. Some people with breast cancer have a gene called BRCA, which increases your risk of breast cancer. If you've inherited these genes, you can't change the risk you face. But only between 5 in 100 and 10 in 100 cancers are caused by these genes.
These are some of the other things that increase your risk of breast cancer:
- Starting your periods early (before age 11).
- Having a late menopause (after age 54).
- Not having children, or having them after the age of 35.
- Getting older. About 8 in 10 cancers are in women who have been through the menopause.
Most of these things have an effect on the levels of oestrogen in your body, which in turn can affect your risk of breast cancer. There's not much you can do about them. Not many women would choose to have children, or have them earlier, just to reduce their own risk of breast cancer.
However, you may be able to do something about some of the things that influence your risk of breast cancer.
These things reduce your risk of breast cancer:
- Not having hormone replacement therapy (HRT) for a long period (more than 5 years).
- Staying at a healthy weight.
- Exercising more.
- Drinking less alcohol.
- If you have a baby, breastfeeding for six months.
How much difference does this make?
Researchers have looked at the evidence about how much difference it would make if women made these changes. Unfortunately, it's not possible to calculate how much difference it would make to an individual woman, because so many other factors (like genes) are involved. Instead, they have calculated how many cases of breast cancer would be avoided every year. At present in the UK, about 44,000 women are diagnosed with breast cancer each year.
The researchers say:
- If half as many women used HRT for more than 5 years, about 2,100 cases of breast cancer would be avoided each year.
- If only 8 percent of women were obese (as was the case in 1980), instead of 23 percent (as is the case today), 1,800 cases of breast cancer would be avoided each year. (Being obese means you are very overweight. You eat far more calories than your body uses and the extra calories get stored as fat.)
- If all women exercised for 30 minutes, 5 times a week, 1,400 cases of breast cancer would be avoided each year.
- If all women drank no more than 2 units of alcohol a day, 200 cases of breast cancer would be avoided each year. (One unit of alcohol is a half pint of ordinary strength lager or a single shot of spirits. A small glass of wine is about 1.5 units of alcohol).
- If 72 percent of new mothers breastfed for 6 months (as they do in Sweden), instead of 21 percent (as in the UK), some cases of breast cancer would be avoided, but the researchers aren't sure how many.
Where does the study come from?
The research was carried out by the Clinical Trial Service Unit and Epidemiological Studies Unit at the University of Oxford. It hasn't been published in a medical journal yet. One of the researchers explained the results at the National Cancer Research Institute (NCRI) Cancer Conference in Birmingham, 30 September to 3 October, 2007.
How reliable are the findings?
Because the research has not been published, we haven't been able to look in detail at the figures. So we don't know how the researchers carried out their calculations.
What does this mean for me?
If you are worried about your risk of breast cancer, it's worth thinking about whether these changes to your lifestyle might be worth making. Only you can decide about that. There are likely to be other factors involved in your decision.
For example, HRT increases the risk of breast cancer more than the other things mentioned. But some women find HRT very helpful if they get bad symptoms while going through the menopause. They might decide that the benefits of HRT outweigh the increased risk. And taking HRT for a short period of time (less than 5 years) won't make as much difference to your breast cancer risk.
Keeping to a healthy weight, exercising and drinking sensibly are all recommended for lots of reasons, not just to reduce the risk of breast cancer. If you do these things, you're likely to be healthier all round. If you wish to lose weight or get advice on an exercise programme, see your GP, who may be able to advise you.
If you are a new mother and wish to breastfeed, you can get advice and support from your midwife or health visitor.
But it's important to remember that, even if you decided to make all these changes, there's no guarantee. Doctors still don't understand everything about what causes breast cancer. There may be genes involved that we don't know about yet, or other risks that haven't yet been discovered.
What should I do now?
If one or more of your close relatives has had breast cancer, and you are worried about your own breast cancer risk, make a routine appointment to talk to your GP. Your GP can ask questions to help work out your risk. You may be offered genetic testing and screening for breast cancer, if you are thought to be at high risk.
If you are concerned about the breast cancer risk of HRT, you could talk to your GP or to a pharmacist.
If you are between the age of 50 and 70, when your risk of breast cancer is higher, you should consider taking part in the national breast cancer screening programme, which offers women a mammogram every three years. Women over the age limit for the programme can ask for a mammogram every three years too. The age range for screening is being extended to between 47 and 73, over the next few years.
To find out more about HRT, see our information on Menopause. To find out more about breast cancer diagnosis and treatment, see our information on Breast cancer.
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© BMJ Publishing Group Limited ("BMJ Group") 2007. All rights reserved
This information does not replace medical advice. If you are concerned you might have a medical problem please ask your Boots pharmacy team in your local Boots store, or see your doctor.
