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Risks and causes

Read about the causes of lung cancer, including lifestyle factors and other medical conditions. And find out what you can do to reduce your risk.

Anything that increases your risk of getting a disease is called a risk factor. Different diseases have different risk factors.

Some risk factors increase the risk of developing lung cancer. But having any of these risk factors doesn’t mean that you will definitely develop cancer.

Risks and causes

Smoking tobacco is one of the biggest causes of lung cancer. More than 8 out of 10 lung cancers (80%) 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 reduces your risk. The sooner you stop, the sooner your risk goes down.

Breathing in other people’s smoke is linked to around 1 in 5 lung cancers in non smokers.

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 around 3 out of 100 lung cancers (3%) 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.

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 1960’s. Even though the use of asbestos was banned in the UK in 1999, some construction workers in older buildings might still be exposed to it. There are strict laws about work that involves asbestos: for example, when working in or repairing structures containing asbestos. Smoking increases the risk from asbestos exposure.

Silica is a substance used in glass making and bricklaying. 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.

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.

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

Tuberculosis (TB) can make scar tissue form in the lungs. People who have had TB have double the risk of lung cancer compared to other people in the population.

Chronic obstructive pulmonary disease (COPD) is also called chronic obstructive airways disease. It means long term lung illnesses such as emphysema and chronic bronchitis. Your risk of lung cancer is higher if you have COPD or lung infection (pneumonia) compared to people who don’t have it.

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.

Radiotherapy for some types of cancer can slightly increase your risk of lung cancer. The cancer types include:

  • Hodgkin lymphoma
  • non-Hodgkin lymphoma
  • testicular cancer
  • womb cancer

Your risk of getting lung cancer following radiotherapy treatment is still small. The benefit to you of treating the cancer outweighs the risk of developing lung cancer.

Women who had radiotherapy for breast cancer in the past might have a slight increase in risk. But modern radiotherapy methods for breast cancer don’t increase lung cancer risk.

HIV and AIDS lower immunity and so do medicines that people take after organ transplants.

People with HIV or AIDS have an increased risk of lung cancer.

People who take medicines to suppress their immunity after an organ transplant also have a higher risk of lung cancer.

There is also a small increased risk if you have an autoimmune condition such as rheumatoid arthritis or systemic lupus erythematosus (SLE).

Other possible causes

Stories about potential causes of cancer are often in the media and 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 either because there is no evidence about them or the evidence is unclear.

Reducing your risk

There are ways to reduce your risk of cancer.

Get detailed information about lung cancer risks and causes

Last reviewed: 
07 Aug 2017
  • Tobacco-attributable cancer burden in the UK in 2010
    DM Parkin
    British Journal of Cancer, 2011. Dec; 105 Suppl 2:S6-S13

  • Preventable exposures associated with human cancers
    VJ Cogliano, R Baan, K Straif and others
    Journal of the National Cancer Institute, 2011. Dec 21;103(24):1827-39

  • Increased risk of lung cancer in individuals with a family history of the disease: a pooled analysis from the International Lung Cancer Consortium
    ML Cote, M Liu, S Bonassi and others
    European Journal of Cancer, 2012 Sep;48(13):1957-68

  • Lung cancer risk among bricklayers in a pooled analysis of case-control studies
    C Consonni, S De Matteis, AC Pesatori and others
    International Journal of Cancer, 2015 Jan 15;136(2):360-71

  • Previous lung diseases and lung cancer risk: a systematic review and meta-analysis
    DR Brenner, JR McLaughlin and RJ Hung
    PLoS One, 2011 Mar 31;6(3):e17479

  • The information on this page is based on literature searches and specialist checking. We used many references and there are too many to list here. Please contact patientinformation@cancer.org.uk with details of the particular issue you are interested in if you need additional references for this information.

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