A risk factor is any factor that is associated with increasing someone’s chances of developing a certain condition, such as cancer. Some risk factors are modifiable, such as lifestyle or environmental risk factors. Others cannot be modified, such as inherited factors and whether someone in the family has had cancer.

Having one or more risk factor does not mean that you will develop cancer. Many people have at least one risk factor but will never develop cancer, while others with cancer may have had no known risk factors. Even if a person with cancer has a risk factor, it is usually hard to know how much that risk factor contributed to the development of their disease.

Factors that are associated with a higher risk of developing lung cancer include the following.^{[1],[2],[3],[4],[5],[6],[7]}

Lifestyle factors

• Current or former tobacco smoking – this is the greatest risk factor for lung cancer. The risk is greatest for people who begin smoking early in life, smoke for longer and smoke more often.

Environmental or occupational factors

• Exposure to second-hand smoke (passive smoking).
• Occupational exposures, such as exposure to radon, asbestos, diesel exhaust and silica. Exposure to asbestos also increases the risk of developing mesothelioma, which starts in the lining surrounding the lungs (the pleura).
• Exposure to air pollution.

Personal factors

• Increasing age.
• Family history of lung cancer.
• History of chronic lung disease, including chronic obstructive pulmonary disease and pulmonary fibrosis.
• Personal history of cancer, including lung cancer, and head and neck cancer.
• History of radiation therapy to the chest for other cancers.
• Infection with HIV (human immunodeficiency virus)
• Certain gene mutations.

Find out more

• Risk factors for lung cancer: an overview of the evidence
• Cancer Australia position statement: Lifestyle risk factors and the primary prevention of cancer