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Risk factors and causes

Smoking cigarettes is the main cause of lung cancer. People who do not smoke can still develop lung cancer, but their risk is much lower.

If someone stops smoking, their risk of developing lung cancer falls quickly. After about 15 years it is almost the same as a non-smoker.

Lung cancer is also more common in older people. Other factors that may increase the risk of developing lung cancer are:

  • Breathing in other people’s smoke (passive smoking). This slightly increases the risk of lung cancer.
  • Exposure to radon gas. High concentrations of radon gas are found in some areas of the country.
  • Exposure to asbestos. Although asbestos is banned in the UK, it was used in areas such as the building industry.
  • People who previously had radiotherapy to the chest. This slightly increases the risk.
  • Having a brother or sister with lung cancer. This may also slightly increase the risk of lung cancer.
  • Exposure to air pollution. Recent research shows air pollution may increase lung cancer risk. But this depends on how much a person is exposed to. For most people, the risk is very small.

Risk factors and causes of lung cancer

Lung cancer is the third most common cancer in the UK. About 46,400 people are diagnosed with it each year. The number of men diagnosed with lung cancer is reducing. But the number of women diagnosed with it is increasing.

Most lung cancers are caused by smoking. There are other risk factors that can increase the chances of developing lung cancer.


Smoking

Smoking tobacco is the cause of most lung cancers and the biggest risk factor. This includes smoking cigarettes, cigars and pipes. The more you smoke, the bigger your risk. Around 9 out of 10 people who get lung cancer (90%) are smokers or ex-smokers. Starting smoking at a young age means the risk is higher.

People who do not smoke can also get lung cancer, but their risk is much lower. About 1 in 10 people who get lung cancer (10%) have never smoked.

Ratio of smokers to non-smokers who help develop lung cancer
Ratio of smokers to non-smokers who help develop lung cancer

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When people stop smoking, their risk of lung cancer gets lower over time. After 12 years of stopping smoking, your risk of lung cancer is about 70% lower than people who do smoke. After about 15 years, it is almost the same as a non-smoker.

I went to my GP, I did a written programme of my intention to give up smoking and was started on Zyban, which personally I found marvellous.

Amy, diagnosed with cancer


Passive smoking

Breathing in other people’s cigarette smoke (passive or second-hand smoking) can slightly increase the risk of lung cancer. The risk is much lower than if you smoke yourself.

In the UK, smoking is now banned in most enclosed public places and workplaces.


Age

Lung cancer is more common in older people. More than 4 in 10 people (44%) who are diagnosed are aged 75 and over. Lung cancer can affect younger people, but it is rare under the age of 40.


Radon gas

In certain parts of the UK, a natural gas called radon can pass from the soil into the foundations of buildings. Exposure to high levels of radon is not common. But it can increase the risk of developing lung cancer, particularly in people who smoke as well.


Asbestos

Asbestos was previously used in building industries. People who have been in prolonged or close contact with asbestos have a higher risk of getting lung cancer. The risk is also bigger if they smoke.

Exposure to asbestos also increases the risk of mesothelioma. This is a cancer of the pleura (membranes that cover the lungs). If you worked with asbestos and have lung cancer or mesothelioma, you may be able to claim compensation. Your lung cancer specialist nurse can give you advice on this.

When I was diagnosed with mesothelioma, the doctors said that I should be looking into claiming compensation. This is because mesothelioma is generally only caused by exposure to asbestos.

George


Previous cancer treatment

People have a slightly increased risk of lung cancer if they have previously had radiotherapy to the chest to treat:

  • lymphoma
  • testicular cancer that has spread.

The risk is bigger if they smoke.

The benefits of this treatment far outweigh the risk of developing lung cancer, especially as these cancers can be cured.


Lowered immunity

Having a lowered immunity because of illness or treatment can increase the risk of lung cancer. People have a lowered immune system if they:

  • have HIV or Aids
  • take immunosuppressant drugs after an organ transplant.


Family risk

People with a parent who had lung cancer have an increased risk of developing it. People who have a brother or sister with lung cancer, especially when diagnosed at a younger age, have a higher risk.

Doctors do not know if this could be caused by a lung cancer gene that runs in the family (inherited), or shared risk factors such as smoking.

If you are worried about lung cancer in the family, you may find it helpful to talk to your GP.

I felt relieved there was a way I could find out about my own cancer risk. I went to my GP, who passed on my details to a genetic specialist.

Aneece


Other causes of lung cancer

Rarely, contact with certain chemicals and substances can cause lung cancer – usually through work.

Recent research has shown that air pollution can cause lung cancer. But it is difficult to know the risk for individual people, as it depends on:

  • the air quality where they live
  • how much pollution they are exposed to.

For most people, the risk is very small. Smoking is the major risk factor for lung cancer.

Lung cancer is not infectious and cannot be passed on to other people.

Back to Diagnosing

How lung cancer is diagnosed

There are lots of possible causes for different symptoms, so it’s important to know what to look out for. If your doctor wants to find out more they might organise different tests or scans.