Lung cancer

What is lung cancer and how is it caused?

What is lung cancer?

Your body is made up of many different types of cells. Normally, your body tightly controls the production of new cells when they’re needed. Cancer develops when certain cells escape from your body’s control and start to change. These abnormal cells, also called cancer cells, start to increase and grow to form a lump. This is called a tumour.

If the cancer starts in your lung, it’s called primary lung cancer. If it starts in another part of your body and spreads to affect your lung, it’s called secondary lung cancer.

The lung is a relatively common site for other cancers to spread to. The management and prognosis of secondary lung cancer is different to that of primary lung cancer.

What are the different types of lung cancer?

There are different types of lung cancer. The main types are:

  • non small cell lung cancer (NSCLC): This is the most common kind of lung cancer. There are three common types of non small cell lung cancer: adenocarcinoma, squamous cell carcinoma and large cell carcinoma.
  • small cell lung cancer (SCLC): This is much less common. It usually spreads more quickly and is often at an advanced stage when it’s diagnosed.
  • mesothelioma:  This is a cancer of the lining of the lung (the pleura) and is often associated with asbestos exposure, commonly through work.

What causes lung cancer?

Anyone can develop lung cancer, but around 85% of cases occur in people who smoke or who used to smoke. Your risk of getting lung cancer increases with the number of cigarettes you’ve smoked and the number of years you’ve been a smoker. If you stop smoking, the risk gets lower over time – after 10 years, your risk of lung cancer falls to half that of a smoker.

Ask your health care professional or pharmacist for help to stop smoking. You’re around 3 times as likely to quit with help from support services and medication. Get help and advice on stopping smoking.

Breathing in other people’s smoke (passive smoking) over a long period can also increase your risk of getting lung cancer. Other environmental factors, such as exposure to asbestos and radon, can increase the risk as well.

It’s increasingly recognised that other factors, such as air pollution, as well as a variety of occupations are associated with an increased risk of getting lung cancer.

People who’ve never smoked are more likely to develop one particular type of lung cancer called adenocarcinoma.

Lung cancer usually affects people over the age of 60. Younger people can develop lung cancer, but this is less common.

Next: Symptoms of lung cancer >

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Last medically reviewed: February 2020. Due for review: February 2023

This information uses the best available medical evidence and was produced with the support of people living with lung conditions. Find out how we produce our information. If you’d like to see our references get in touch.