Breast cancer is the most common type of cancer in the world for women, with the UK being one of the highest risk areas. It is actually also the fifth most preventable cancer, so what can we do about it to reduce our risk?
We all know how important keeping active and eating a balanced diet is for our health, but it might be surprising to know that diet and lifestyle contributes to 40% of cancer risk, and therefore plays a very important role in the prevention of breast cancer.
Hormones play an important role in the development of breast cancer. Our exposure to oestrogen, a powerful female sex hormone, can increase our risk. Oestrogen is mainly produced in the ovaries and so, if we start our periods early and experience menopause late, we will have a longer and therefore higher exposure to oestrogen. The reverse also applies, whereby if we start our periods late and have an early menopause, this can lessen the risk of breast cancer.
Breast cancer is more common in postmenopausal women. The reason for this is thought to be because oestrogen is mainly produced in the ovaries, but after the menopause, oestrogen is produced in the fatty tissue of the breast. Therefore, risk factors for the development of breast cancer are categorised into pre and postmenopausal women.
We are unable to change some risk factors, such as our genetic predisposal, our age and our menstrual development, but there are many others, such as smoking, alcohol consumption, diet and overall fitness, that we can do something about.
A diet in which we consume more calories than is necessary can promote early breast development and puberty, and late menopause. As stated earlier, this prolonged exposure to oestrogen increases our risk of developing breast cancer. So, reducing this risk begins as early as childhood, and is something we can be thinking about when beginning a family and bringing up our children. Scientists have claimed that even just having a greater birth weight can lead to premenopausal breast cancer.
Eating too many energy dense foods can lead to being overweight or obesity. Interestingly, surplus body fat increases your risk if you are postmenopausal but was found to be protective in premenopausal women. Obese women often have menstrual cycles that do not result in ovulation, thus exposing them to less oestrogen. However, obesity is a risk factor for many other diseases and cancers, and so we should aim to be a healthy weight throughout our adult life. Obesity is also likely to continue throughout adult life and after the menopause, which would lead to an eventual increase in breast cancer risk.
Excess body weight can create an environment where levels of hormones circulating around the body are high, including insulin, oestrogen and growth factors. These all encourage cancer development, by promoting growth of cancer cells. Carrying extra weight around the abdomen and gaining extra weight in adulthood are also likely to increase risk of postmenopausal breast cancer.
The more we drink, the greater our risk of developing breast cancer for both pre and postmenopausal women. For a teetotal woman, the average risk over her lifetime of developing the disease is 11 or 12 out of 100. For a woman who consumes two units of alcohol on a daily basis, this risk increases slightly to 13 or 14 out of 100. For a woman who consumes double that amount, the risk increases further to 16 or 17 out of 100.
People who consume high amounts of alcohol are likely to absorb lower amounts of essential nutrients from nutritious foods. This lack of nutrients can also make you more susceptible to developing cancer. Additionally, alcohol may interfere with the metabolism of oestrogen, which can cause an increase in oestrogen levels in the body.
When we breastfeed, our menstrual periods stop, and so we have less exposure to oestrogen and other cancer-promoting hormones. Also, during lactation, the breast tissue is exfoliated and helps to get rid of any cells that may have become damaged.
Therefore, strong evidence shows that if you breastfeed after pregnancy, this can decrease your risk of developing breast cancer for both pre and postmenopausal women. The risk decreases further the longer you breastfeed, so amongst all other benefits that breastfeeding has for your baby, it also has benefits for you.
For postmenopausal women, physical activity is likely to decrease the risk of breast cancer development, however it is unclear how often, how long and how intense the activity should be. The evidence suggests that physical activity decreases the levels of oestrogens in the body for postmenopausal women.
You may have heard that having a diet high in fat increases breast cancer risk. This may be true for postmenopausal women – the theory being that high fat diets produce more oestrogen in the body – however the evidence is weak. Nevertheless, a diet high in fat can lead to obesity and, because high fat foods tend to lack essential nutrients, we may be more prone to developing cancer.
Phytoestrogens can bind to oestrogen receptors, blocking the action of oestrogen, and so this can help to reduce oestrogen production within the body. Phytoestrogens occur in plant foods, soya and soya products, seeds, nuts and beans. Consuming high amounts of these foods has been associated with a lower incidence of breast cancer.
However, there is some evidence suggesting that they may stimulate the progression of disease, and so it is advised to remain cautious about including high amounts of phytoestrogen-rich foods in your diet, particularly if you are at high risk of developing breast cancer.
These foods, and other foods containing fibre such as wholegrains, beans and pulses can be protective for many diseases and cancers. A higher intake of fruit and vegetables can reduce breast cancer risk, but evidence around fibre is weak. Nevertheless, due to the proven benefits of these foods, including them in our diet is recommended for good all-round health.
In summary, it’s important to understand your risk when it comes to breast cancer. Regular medical check ups can help to assess your risk. Eating a diet based around the government’s Eatwell Plate, ensuring you are a healthy weight throughout life, and keeping active can reduce your risk significantly.
For more information on other risks associated with breast cancer, please read our article, Breast cancer risk factors.
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