Lung cancer

Graphic of lung cancer statisticsHow diet, nutrition and physical activity affect lung cancer risk. In total, we analysed 124 studies from around the world, covering nearly 14 million adults and over 122,000 cases of lung cancer.

The lungs are part of the respiratory system and lie in the thoracic cavity. Air enters the lung through the trachea which divides into two main bronchi, each of which is subdivided into several bronchioles which terminate in clusters of alveoli.

> Find the latest lung cancer statistics

What causes lung cancer?

Smoking is the main cause of lung cancer. It is estimated that over 90% of cases among men and over 80% among women worldwide are attributable to tobacco use. Passive smoking is also a cause of lung cancer.

Our Expert Panel has also reviewed the evidence on diet, weight, physical activity and the risk of lung cancer.

There is strong evidence that:

There is some evidence that:

  • consuming red meat, processed meat and alcoholic drinks might increase the risk of lung cancer
  • in current smokers and former smokers, consuming vegetables and fruit might decrease the risk of lung cancer
  • consuming foods containing retinol, beta-carotene or carotenoids might decrease the risk of lung cancer
  • in current smokers, consuming foods containing vitamin C might decrease the risk of lung cancer
  • in people who have never smoked, consuming foods containing isoflavones (constituent of plants with oestrogen-like properties) might decrease the risk of lung cancer
  • being physically active might decrease the risk of lung cancer

> Download our 2018 lung cancer report

> Browse all our resources and toolkits

Other causes of lung cancer

In addition to smoking and the findings on diet, nutrition and physical activity outlined above, other established causes of lung cancer include:

Previous lung disease

A history of emphysema, chronic bronchitis, tuberculosis or pneumonia is associated with an increased risk of lung cancer. People with antibodies to Chlamydia pneumoniae, a type of bacterium that can cause chest infections, have an increased risk of lung cancer.

Other exposures

Occupational exposure to asbestos, crystalline silica, radon, mixtures of polycyclic aromatic hydrocarbons and heavy metals are associated with an increased risk of lung cancer as well as indoor air pollution from wood and coal burning for cooking and heating.

Pathogenesis: how does lung cancer develop?

Carcinogens in tobacco smoke and other inhaled particles, such as coal tar or asbestos, can interact directly with the DNA of lung cells. Because the whole lung is exposed to inhaled carcinogens, several sites may accumulate different cancerous changes, leading to multiple cancers originating in different types of cells. Chronic inflammation may also play a role in the development of lung cancer, with cancerous changes occurring as a response to exposure to irritants and repeated injury.

Molecular changes in the mucosa of smokers that predispose to cancer are now being identified. Dysplasia and carcinoma in situ are histopathologic changes predictive of future development of invasive carcinoma.

This process may take many years or decades depending upon the exposure to cancerinitiating and cancer-promoting components. People with lung adenocarcinomas may have an associated history of chronic lung disease, such as scleroderma, rheumatoid disease, sarcoidosis or tuberculosis.

Full references and a summary of the mechanisms underpinning all the findings can be found in the lung cancer report.

Emerging research on lung cancer

We fund research on lung cancer through our grant programme. Read about the latest findings and ongoing projects in our database of projects.

Diet and Cancer Report 2018

In 2018, World Cancer Research Fund International published Diet, Nutrition, Physical Activity and Cancer: a Global Perspective on behalf of AICR, WCRF and WKOF. This was the third in our series of major reports looking at the many ways in which our diets, and how active we are, affect our cancer risk. You can find out much more about lung cancer by downloading a pdf of the relevant chapter in the 2018 report. Please note, however, that this webpage may have been updated since the report was published.

Published findings in peer-reviewed journals

Selected findings from this report have been published in peer-reviewed journals. Details of the papers and links to the abstract in PubMed are below:

Blood concentrations of carotenoids and retinol and lung cancer risk: an update of the WCRF-AICR systematic review of published prospective studies. Abar L, Vieira AR, Aune D, Stevens C, Vingeliene S, Navarro Rosenblatt DN, Chan DS, Greenwood DC, Norat T. Cancer Med. 2016 Aug;5(8):2069-83. Abstract

Fruits, vegetables, and lung cancer risk: a systematic review and meta-analysis. Vieira AR, Abar L, Vingeliene S, Chan DS, Aune D, Navarro-Rosenblatt D, Stevens C, Greenwood D, Norat T. Cancer Ann Oncol. 2016 27 (1): 81-96. Abstract