The most common cause of lung cancer is smoking. It is one of the few cancers where there is a clear cause in many cases. Lung cancer is predominantly a disease of the elderly; almost 70% of people diagnosed with lung cancer are over 65 years of age, while less than 3% of lung cancers occur in people under 45 years of age.
- Cigarette smoke contains more than 4,000 chemicals, many of which have been identified as causing cancer. A cell that is damaged may become cancerous over a period of time.
- In general, though, a smoker’s chances of developing cancer depends on the age that the person began smoking, how long the person has smoked and how many cigarettes per day the person smokes.
- Passive smoking may also increase the risk for developing lung cancer.
- Air pollution from motor vehicles, factories, and other sources probably increase the risk for lung cancer.
- Asbestos exposure increases the risk of lung cancer by nine times. A combination of asbestos exposure and cigarette smoking raises the risk to as much as 50 times.
- Radon is a by-product of naturally occurring radium, which is a product of uranium. The risk for lung cancer increases with significant long-term exposure to radon, although no one knows the exact risk.
- Air pollution may cause lung cancer.
- 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. Tuberculosis (TB) can make scar tissue form in the lungs.
- Pipe and cigar smoking also can cause lung cancer, although the risk is not as high as with cigarette smoking.
- Survivors of lung cancer have a greater risk of developing a second lung cancer than the general population has of developing a first lung cancer.
- Certain reports indicate that diet low in fruits and vegetables may increase the chances of getting cancer, if you are exposed to tobacco smoke.
- Viruses are known to cause lung cancer in animals and recent evidence suggests similar potential in humans.
