Risks and causes of lung cancer

Smoking tobacco is the biggest cause of lung cancer in the UK. There are some other risk factors that can increase your risk of developing lung cancer.

What is a risk factor?

Anything that can increase your risk of getting a disease is called a risk factor.

Different cancers have different risk factors.­ Having one or more of these risk factors doesn't mean you will definitely get that cancer.

Smoking tobacco

Smoking tobacco is the biggest cause of lung cancer in the UK. More than 60 out of 100 lung cancers (more than 60%) are caused by smoking. This includes breathing in other people’s cigarette smoke.

Even light or occasional smoking increases the risk of lung cancer. But your risk increases more the longer you smoke and the more you smoke. Stopping smoking is the best thing you can do for your health. The sooner you stop, the better.

Chemicals and workplace risks

Some substances increase the risk of lung cancer. These include asbestos, silica, and diesel exhaust. People can be exposed to these through their work.

Asbestos was used in shipbuilding and the construction industry in the 1960s. Asbestos was banned in the UK in 1999, but some construction workers in older buildings might still be exposed to it. There are strict laws about work that involves asbestos. This might be, for example, when working in or repairing structures containing asbestos. Smoking increases the risk from asbestos exposure.

Silica is a substance used in some construction and material industries. These include industries such as glass making and bricklaying. People who have worked as bricklayers can have a slightly increased risk of lung cancer. It can cause a condition known as silicosis, which increases the risk of lung cancer. 

Diesel engine exhaust fume exposure increases the risk of lung cancer. So, people who are regularly exposed to exhaust fumes through their jobs have a higher risk of developing lung cancer. This includes professional drivers and mechanics.

Air pollution

We know that air pollution can cause lung cancer. The risk depends on the levels of air pollution you are regularly exposed to. At UK levels, the extra risk for each person is likely to be small. Exposure to outdoor air pollution causes 8 out of 100 (8%) lung cancer cases in the UK.

Previous lung disease

Previous lung diseases can increase your risk of lung cancer. These risks are usually higher in smokers.

Chronic obstructive pulmonary disease (COPD) is also called chronic obstructive airways disease. It means long term lung illnesses such as emphysema and chronic bronchitis.  COPD usually develops because of long-term damage to your lungs from breathing in a harmful substance, usually cigarette smoke. Your risk of lung cancer is higher if you have COPD or lung infection (pneumonia) compared to people who don’t have it.

Idiopathic pulmonary fibrosis (IPF) also increases the risk of a lung cancer developing. This is compared to people who don’t have it.

Exposure to radon gas

Radon gas is a naturally occurring radioactive gas that comes from tiny amounts of uranium present in all rocks and soils. Radon gas can build up in homes and other buildings. The highest levels are in south west England but higher than average levels may be found in many other parts of the UK. 

Exposure to radon causes a small number of lung cancers in the UK. The risk increases if you smoke. So, it’s even more important to stop smoking if you live in a high radon area.

Family history of lung cancer

Your risk of lung cancer is higher if you have a close relative (such as a parent or sibling) who has had lung cancer.

Researchers are looking at how our genes could affect our risk of lung cancer.

High doses of beta-carotene

Some research has shown that taking high doses of beta-carotene (20 to 30 milligrams per day) from supplements could increase the risk of lung cancer in people who smoke. It might also increase the risk in people who used to smoke. Speak to your doctor or pharmacist if you smoke, or used to smoke, and are considering starting a high dose beta-carotene supplement.

There is no good evidence that beta-carotene supplements increase the risk of any other type of cancer.

More information on risk factors for lung cancer

We have more detailed information for health professionals about lung cancer risks and causes.

Other possible causes

There are often stories about potential causes in the media. It isn’t always clear which ideas are supported by evidence. There might be things you have heard of that we haven’t included here. This is because either there is no evidence about them or it is less clear.

Reducing your risk

There are ways you can reduce your risk of cancer.