The main cause of lung cancer is tobacco smoke (cigarettes, pipes or cigars), although not everyone who smokes will get lung cancer. Harmful substances in smoke damage the lung cells. Inhaling second-hand smoke from people smoking nearby can also cause lung cancer in some people who do not smoke.
You may also be at risk for lung cancer if you:
- Are older than 40 years. Most people are older than 65 years when they are diagnosed with lung cancer
- Have contact with substances such as radon (a radioactive gas), asbestos, arsenic, chromium, nickel and polluted air
- Have family members who have had lung cancer