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.

CUP lung cancerIn total, this report analyses 124 studies from around the world, covering nearly 14 million adults and over 122,000 cases of lung cancer.

Incidence and survival rates

Lung cancer is the third most common cancer worldwide. About 1.8 million new cases of lung cancer were recorded globally in 2012, accounting for 13 per cent of all new cases of cancer.

Lung cancer is the most common cause of death from cancer, estimated to be responsible for nearly one in five cancer deaths. Lung cancer survival is mostly determined by the stage at which it is diagnosed, with later-stage diagnosis having poorer survival.

In men, lung cancer is the most common cancer diagnosed, and the highest lung cancer rates are in Central and Eastern Europe and Eastern Asia. In women, lung cancer is the third most common cancer, and the highest rates are in North America, Northern Europe and Eastern Asia.

Lifestyle factors and lung cancer risk

In this report from our Continuous Update Project (CUP) – the world’s largest source of scientific research on cancer prevention and survivorship through diet, nutrition and physical activity – we analyse global research on how certain lifestyle factors affect the risk of developing lung cancer. This webpage forms part of the World Cancer Research Fund/American Institute for Cancer Research Third Expert Report Diet, Nutrition, Physical Activity and Cancer: a Global Perspective.

Findings on 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

See more graphics in our toolkit.

Other causes of lung cancer

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

  • smoking

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

  • 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

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.

How the research was conducted

The global scientific research on diet, nutrition, physical activity and the risk of lung cancer was systematically gathered and analysed, and then independently assessed by a panel of leading international scientists in order to draw conclusions about which of these factors increase or decrease the risk of developing lung cancer.

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

This webpage is a summary.

For much more, download the full chapter.