Lung cancer happens when there is DNA damage to the cells in the lungs. The main cause of this is smoking tobacco. While the causes of lung cancer are not fully understood, there are a number of other factors associated with the risk of developing the disease. These factors include:
- environmental factors such as passive smoking, random exposure and occupational exposures, such as asbestos and diesel exhaust
- a family history of lung cancer
- previous lung diseases such as lung fibrosis, chronic bronchitis, emphysema and pulmonary tuberculosis (TB).
Tobacco smoke contains more than 7000 chemicals, 69 of which can lead to the development of cancer. If you smoke, youare 15 to 30 times more likely to get lung cancer or die from lung cancer than someone who does not smoke.
While smoking cigarettes is the biggest risk factor, using other types of tobacco products can also increase your risk of developing lung cancer and other types of cancer, such as oesophageal cancer and mouth cancer. These products include:
- pipe tobacco
- snuff (a powdered form of tobacco)
- chewing tobacco.
Smoking cannabis has also been linked to an increased risk of lung cancer. Most cannabis smokers mix their cannabis with tobacco. While they tend to smoke less than tobacco smokers, they usually inhale more deeply and hold the smoke in their lungs for longer.
Even smoking cannabis without mixing it with tobacco is potentially dangerous. This is because cannabis also contains substances that can cause cancer.
Even if you do not smoke, frequent exposure to other people's tobacco smoke (passive smoking) can increase your risk of developing lung cancer. Living with a smoker is estimated to increase a nonsmoker’s chances of developing lung cancer by 20 to 30 percent.
Last reviewed: November 2017