Dr Dillner's health dilemmas: can I do more to prevent breast cancer?

Studies have shown that staying active is one of the most important measures to lower your risk level
Woman jogging
Exercise can reduce your risk. Photograph: Brad Wilson/Getty Images


A more recent report in the British Journal of Cancer looked at 48,385 cases of breast cancer and found that 26.8% were due to environmental factors. What are these factors and how can you do more to alter them?

The solution

There are some risk factors for breast cancer that you cannot change. Being a woman increases your chances (one man gets breast cancer for every 150 women). As do genetic factors, thought to account for 5-10% of breast cancers. There is a slightly higher risk if you start your period before the age of 12 or do not have your menopause until after the age of 55; if you have had radiation therapy to your chest to treat some types of lymphoma; if you don't have children or wait until you are over 30. If you do have kids, breastfeeding seems to help protect you because it reduces the number of menstrual cycles you have, which is equivalent to starting your periods later.

You can probably guess the main things you need to do to make a difference. The study in the British Journal of Cancer found that 6.4% of breast cancers diagnosed in 2010 were attributable to drinking more than the Department of Health's recommended weekly amount of alcohol (14 units). It also found that 8.7% were due to women being overweight or obese. This is particularly relevant for breast cancer after the menopause and is related to the way fat cells raise oestrogen levels. Getting fat around your waist is more risky than putting it on your hips and thighs. There is nothing much that you can do about that except eat healthily and avoid putting on fat anywhere.

The other big factor seems to be the amount of exercise you do. Being inactive was responsible for 3.4% of breast cancers in the British Journal of Cancer report. There is no consensus on how much exercise you need to protect you but a study in the Medical Journal of Australia suggests 30 minutes of moderate activity, such as walking, for five days a week.

Other factors are likely to only raise your risk a little. There is no evidence for antiperspirants or abortion increasing the risk. Hormone replacement therapy increases risk by only a small amount.

While the causes of breast cancer are often complex and related to several factors, exercising more, eating healthily and limiting how much alcohol you drink will help, and also reduce your risk of other cancers.