- The more you smoke, the more likely you are to get lung cancer but it is the length of time you have been a smoker that is most important.
- Starting smoking at a young age greatly increases the risk
- As soon as you stop smoking your risk of lung cancer starts to go down
- Passive smoking (breathing in other people's cigarette smoke) can increase the risk of lung cancer.
Passive smoking: Passive smoking, or the inhalation of tobacco smoke from other smokers, is also an established risk factor for the development of lung cancer. Research has shown that non-smokers who reside with a smoker have a 24% increase in risk for developing lung cancer when compared with other non-smokers.
Exposure to radon gas: Radon is the second biggest cause of lung cancer after smoking. Radon gas is a naturally occurring radioactive gas which comes from tiny amounts of uranium present in all rocks and soils. The radon gas can build up in homes and other buildings.
Exposure to chemicals: A number of substances that occur in the workplace may cause lung cancer. In particular, these include asbestos, silica, and diesel exhaust.
Air pollution: Based on a large European study, researchers think that 5-7% of lung cancers in non-smokers are due to outdoor air pollution. The use of coal for cooking and for heating the home, and a high level of smokiness in the home, has been shown to increase lung cancer risk.
Previous lung disease: Having had a disease that caused scarring in the lungs may be a risk factor for a type of lung cancer called adenocarcinoma of the lung.
Family history of lung cancer: If you have a first degree relative with lung cancer your risk of lung cancer is increased by 51%. The risk is even greater if a brother or sister has lung cancer. This risk is regardless of whether or not you smoke.
Lowered immunity: HIV and AIDS lower immunity and so do drugs that people take after organ transplants. An overview of research studies shows that people with HIV or AIDS have a risk of lung cancer that is 3 times higher than people who do not have HIV or AIDS. People who take drugs to suppress their immunity after an organ transplant have double the usual risk of lung cancer.
The presence of certain diseases of the lung, notably chronic obstructive pulmonary disease (COPD), is associated with a slightly increased risk (four to six times the risk of a nonsmoker) for the development of lung cancer even after the effects of concomitant cigarette smoking are excluded.
Personal history of lung cancer
Survivors of lung cancer have a greater risk than the general population of developing a second lung cancer. In survivors of small cell lung cancers (SCLCs) the risk for development of second cancers approaches 6% per year.
Workplace exposure: Studies have shown a link between being exposed to the following substances and an increased risk of lung cancer:
- Radon gas.
- Tar and soot.
These substances can cause lung cancer in people who are exposed to them in the workplace and have never smoked. The risk of lung cancer is higher in people who are exposed and also smoke.
Beta carotene supplements in heavy smokers: taking beta carotene supplements (pills) increases the risk of lung cancer, especially in smokers who smoke one or more packs a day. The risk is higher in smokers who have at least one alcoholic drink every day.