What causes cancer?
Cancer is caused by the uncontrolled growth of cells in your body. This can happen when genes, the instructions that tell your cells how to function, are damaged. Cells can normally repair this damage. But if they don’t, and the cells keep growing and multiplying, they may eventually form a tumour.
This damage to your genes can happen randomly, it can be inherited from a parent, or it can be caused by external factors you’re exposed to. Some cancers are linked to long-term inflammation, which you might have if you’re overweight. So your risk of cancer can depend on several different things. Most cancers happen because damage builds up as you age - half of all cancers are in people older than 70.
What are the main risk factors for cancer?
Other than age, there are several key risk factors for cancer. These include:
- Tobacco use
- Ultraviolet light, such as sunlight and light from sun beds
- Some viruses, such as human papillomavirus (HPV) and hepatitis B virus (HBV)
- Alcohol consumption
- A diet high in red and processed meat
- Being overweight or obese – which means you have a body mass index (BMI) higher than 25
Some factors increase your risk of certain types of cancer. For example, smoking is the leading cause of lung cancer. A diet high in red and processed meat can increase your risk of bowel cancer.
But some factors can more generally increase your risk of cancer. For example, being overweight increases your risk of at least 13 types of cancer, including breast cancer, bowel cancer, pancreatic cancer and oesophageal cancer. Alcohol is a risk factor for seven types of cancer, including liver cancer, bowel cancer, and breast cancer.
You can learn more about how these factors affect your cancer risk by using our cancer risk tool.
Can I prevent cancer?
Not all cancers can be prevented, but there are steps you can take to reduce your risk of some cancers. Over a third of cases of the most common cancers could be prevented by making lifestyle changes. By making these changes you can reduce your risk of cancer, as well as develop habits that help improve your general health.
How do I reduce my risk of cancer?
Making healthy lifestyle changes is one way of limiting your exposure to many of these cancer risk factors. Here are some steps you can take to manage your risk of cancer.
- Stop smoking – tobacco contains more than 60 chemicals that can cause cancer, and smoking is the main cause of cancer in the UK. Stopping smoking also lowers your risk of diabetes and cardiovascular disease
- Keep to a healthy weight – being overweight or obese is the second leading cause of cancer in the UK. If your BMI is over 25, try to introduce regular exercise and a healthy, balanced diet into your routine. This will help you lose weight safely
- Use sunscreen and reduce your exposure to ultraviolet radiation. Sunburn increases your risk of skin cancer, and sun exposure over a long time also increases your risk
- Eat a balanced diet – try to limit your intake of red and processed meat and eat foods that are high in fibre. This will help lower your risk of bowel cancer. You should aim to eat at least five portions of fruit or vegetables each day, too
- Stay physically active. World Health Organization Guidelines recommend you get 150 minutes of exercise each week, which helps maintain a healthy weight and lowers your cancer risk. Try setting some goals for each week – it’ll keep you motivated!
- Limit your alcohol intake – your cancer risk increases with the amount of alcohol you consume, and any type of alcohol can cause cancer. There are several ways you can cut down on alcohol. Why not have some drink-free days, or reduce the size of your drinks?
Some of these habits could be picked up as part of a bigger lifestyle change. For instance, if you stop smoking, you might find it easier to exercise, which can help you maintain a healthy weight. Eating a healthy, balanced diet can also help you maintain a healthy weight.
Many of these are long-term changes – to see the benefit, you’ll need to stick with them. But by adopting healthier habits like these, you’ll help to reduce your risk of cancer and look after your general health in the long run.
The cancer risk tool also gives advice on changes you can make to lower your risk of cancer, based on the answers you provide. Why not try it out?