The main cause of lung cancer is tobacco smoke (from cigarettes, pipes and cigars), although not everyone who smokes will get lung cancer. Harmful substances in the smoke damage the lung cells. Inhaling secondhand smoke from people smoking nearby can also cause lung cancer in 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 diagnosed with lung cancer
- Contact certain substances, such as radon (a radioactive gas), asbestos, arsenic, chromium, nickel and air pollution
- Have family members who have had lung cancer