What are the risk factors?

A risk factor is anything that is known to increase a person’s chances of developing a certain condition, such as cancer. It’s possible to avoid or reduce the impact of some risk factors. Called modifiable risk factors, these include smoking tobacco or exposure to air pollution. Other risk factors, such as having a family history of lung cancer, can’t be avoided.

Not all causes of lung cancer are fully understood, and some people develop lung cancer without having any known risk factors. The factors listed below are known to increase the risk of lung cancer. Having these risk factors does not mean you will develop lung cancer, but if you are concerned, talk to your doctor.

Lifestyle factors

Tobacco smoking – In Australia, about 85% of lung cancer cases in men and 70% in women are estimated to be a result of smoking tobacco. The earlier a person starts smoking, the longer they smoke and the more cigarettes they smoke, the higher the risk of developing lung cancer.

People who have never smoked can also get lung cancer. About 15% of cases occur in men who have never smoked, and about 30% of cases occur in women who have never smoked.

Environmental or work-related factors

• Second-hand smoking – Breathing in other people’s tobacco smoke (second-hand smoke) can cause lung cancer. Living with someone who smokes is estimated to increase the risk of lung cancer by up to 30% in people who don’t smoke.
• Exposure to asbestos – People who are exposed to asbestos are more likely to develop lung cancer or pleural mesothelioma. Although the use of asbestos in  building materials has been banned in Australia since 2004, asbestos may still be found in some older buildings and fences.
• Exposure to other elements – People who have been exposed to radioactive gas (radon), such as uranium miners, have an increased risk of lung cancer. Outdoor and indoor air pollution (e.g. exposure to household air pollution from gas or wood-burning cooking or heating) is another risk factor. Contact with the processing of arsenic, silica, cadmium, steel and nickel, and exposure to diesel engine exhaust while working may also be risk factors.

Personal factors

• Family history – You may be at slightly higher risk if a family member has been diagnosed with lung cancer.
• Other conditions – Having another lung disease (e.g. lung fibrosis, chronic bronchitis, pulmonary tuberculosis, emphysema) or human immunodeficiency virus (HIV) may increase the risk of lung cancer.
• Older age – Lung cancer is diagnosed mostly in people aged over 60 years, although it can occur in younger people.