How physical activity prevents cancer
Being physically active isn’t just good for your heart: there is lots of evidence that it can also reduce the risk of developing breast, bowel or womb cancer. Keeping active could help to prevent around 3,400 cases of cancer every year in the UK.
Being active has a wide range of benefits for the body. And it’s likely that different effects are important in helping prevent different types of cancer. This page explains the theories with the best evidence behind them.
How does physical activity affect hormone levels?
Hormones are chemical messages that get carried around our bodies in our blood. They help tell our bodies and cells what to do. Being physically active can change the levels of some hormones, including oestrogen and insulin.
In women, physical activity can lower the level of oestrogen. Oestrogen is thought to fuel the development of many breast and womb cancers, so reducing the levels of this hormone could help to reduce the risk.
Activity can also reduce the amount of insulin in our blood. Insulin is very important in controlling how our bodies use and store energy from food. Changes in insulin levels can have effects all over the body. And scientists think insulin can turn on signals that tell cells to multiply. Because cancer starts when cells multiply out of control, lowering insulin levels could help stop some types of cancer from developing.
How does physical activity prevent bowel cancer?
Physical activity helps food move through our bowels. When food moves through our bowels quickly this reduces the amount of time that the inside lining of the bowel is in contact with any harmful chemicals, like those released when you consume alcohol or red and processed meat. So there’s less chance of them being able to cause damage that could lead to cancer.
Being active also helps control levels of inflammation in the bowel. Inflammation is a normal part of the way our bodies react to injury or infections. But it can sometimes cause even more damage, particularly when it keeps happening in the same place. This can lead to the cells multiplying much more frequently than usual, to replace dead and damaged cells, increasing the chances of mistakes that could lead to cancer.
Is physical activity just good for us because of its effects on weight?
Being physically active, along with a healthy, balanced diet, can also help you manage your weight. And keeping to a healthy weight is another great way to reduce the risk of developing cancer and other diseases.
But physical activity has benefits above and beyond weight control, and it doesn’t only reduce the risk of cancer through its effects on weight.
How does physical activity benefit cancer patients?
There is also good evidence that being active can help people during and following cancer treatment. If you are a cancer patient and want to be more active, discuss with your doctor what would work best for you.