What causes lung cancer?

What causes lung cancer?

Tobacco smoke is the primary cause of lung cancer. Although nonsmokers can get lung cancer, the risk is about 10 times greater for smokers and is also increased by the number of cigarettes smoked per day.

If you are a heavy smoker consuming more than 20 cigarettes a day, the risk of developing lung cancer is about 30 to 40 times higher than if you don't smoke.

The main reason for the substantial increase in the disease over the last 50 years has been the increase in the number of people who smoke cigarettes. This has resulted from the industrial production and marketing of tobacco.

The risk of lung cancer in an ex-smoker falls to the same level as a nonsmoker after about 15 years.