Risk factors and causes of lung cancer

Smoking is the cause of most lung cancers, but there are a number of other risk factors and causes that can increase your chance of developing the disease.

A risk factor is something that increases your chance of developing a health condition. For example, age is a risk factor - most people who develop cancer are over 65. Having a particular risk factor doesn’t mean you’ll definitely get cancer. However, sometimes people without any known risk factors can develop cancer. 

Smoking Back to top

Cigarette smoking is the cause of most lung cancers. The more you smoke, the greater your risk of developing lung cancer. It’s also more likely to develop in people who start smoking at a young age. Filtered and low-tar cigarettes may slightly reduce a person’s risk of developing cancer, but the risk is still far higher than that of a non-smoker.

People who don’t smoke can also develop lung cancer. Approximately 10-15% of people (around 1 in 10) who get lung cancer will never have smoked.

Lung cancer is more common in men, as more men used to smoke than women. However, the number of men diagnosed with lung cancer in the UK has fallen over the last 30 years. And, as more women have started smoking, the number of women developing lung cancer has increased. 

Stopping smoking

If someone stops smoking, their risk of developing lung cancer falls quickly. After about 15 years, the risk of them developing the disease is similar to that of a non-smoker.

Passive smoking

Breathing in other people’s cigarette smoke (passive smoking) may slightly increase the risk of lung disease and cancer. But the risk is still much lower than if you smoke yourself.

Pipes and cigars

Although pipe and cigar smokers have a lower risk of lung cancer than cigarette smokers, they’re still at a much higher risk than non-smokers.

Cannabis

Smoking cannabis may also increase the risk of developing lung cancer. Less is known about the harmful effects of smoking cannabis, but it’s believed to cause similar damage to the cells in the lungs as smoking tobacco.

Radon gas Back to top

In some parts of the UK, such as the South West and the Peak District, a naturally-occurring gas called radon can pass from the soil into the foundations of buildings. Exposure to high concentrations of radon can increase the risk of developing lung cancer. Smokers who are also exposed to radon have an increased risk of developing lung cancer.

If you’re worried about the level of radon in your house, you can get a radon detector from the radiation protection division of the Health Protection Agency. They can also advise you on what you can do to reduce the risk.  

Age Back to top

Lung cancer is more common in older people. About 80% of lung cancers (8 in 10) are diagnosed in people over 60. Lung cancer rarely affects people under 40.

Genetic risk Back to top

Some people with a close relative who has had lung cancer may be at an increased risk of it themselves, although the increase in risk is very small.

If you’re concerned about a family history of lung cancer, you may find it helpful to read our information on Cancer Genetics|. You can also talk to your GP. 

Asbestos Back to top

Asbestos is a natural mineral that was used in different building industries. People who have been in prolonged or close contact with asbestos have a higher risk of developing lung cancer, especially if they smoke. Asbestos and tobacco smoke act together to increase the risk.

Many people have been in contact with asbestos during their working lives. Low-level exposure only slightly increases the risk of lung cancer (compared to the risk from smoking), while heavy exposure may result in a much higher risk.

If you have worked with asbestos and develop lung cancer, you may be able to claim compensation. You can get more advice about this from your cancer specialist, from support organisations|, or by calling our cancer support specialists|.

Asbestos exposure also increases the risk of mesothelioma|, a cancer of the membranes that cover the lungs.

Past cancer treatment Back to top

People who’ve been treated for some types of cancer may have a slightly increased risk of developing lung cancer many years later.

Women who were treated with radiotherapy for breast cancer and who smoke may have an increased risk of lung cancer.

People who’ve been treated for some types of lymphoma using radiotherapy to the chest area, and men who’ve been treated for testicular cancer using radiotherapy to the chest area, have a slightly increased risk of lung cancer, especially if they smoke.

However, the risk of developing lung cancer is far outweighed by the benefits of the initial treatment.

Lowered immunity Back to top

People whose immunity is lowered by illnesses such as HIV or AIDS, or who have to take drugs that lower their immunity (immunosuppressants) after having an organ transplant, have a higher risk of developing lung cancer. However, the reason for taking the immunosuppressants outweighs the possible risk of lung cancer.   

Other causes Back to top

Contact with certain chemicals and substances - such as silica, uranium, chromium and nickel - can cause lung cancer, but this is rare.

Air pollution has been suggested as a cause of lung cancer, but this is difficult to prove.