More than 85 percent of all lung cancer cases are related to tobacco, either by smoking or breathing secondhand smoke, and approximately half of all continuing smokers will die from a disease caused by smoking.
The risk of lung cancer increases with the length of time and number of cigarettes you’ve smoked. Lung cancer occurs most frequently among people older than age 50 who have smoked for many years.
Cigarette smoke contains more than 7,000 chemicals, many of them cancer-causing substances (carcinogens) that damage the cells in the lungs. At first your body may be able to repair the damage caused by the carcinogens, but with repeated exposure, the damage causes your cells to act abnormally and eventually become cancerous.
Other Risk Factors
Other risk factors for lung cancer include:
- Exposure to environmental carcinogens, including:
- Radon (a naturally occurring radioactive gas that results from the breakdown of uranium in soil and rocks)
- Chemicals or minerals, such as arsenic, beryllium, cadmium, chromium, nickel, or silica
- Diesel exhaust
- Radiation exposure from occupational, medical, or environmental sources
- History of lung cancer, lymphoma, or head or neck cancer
- History of emphysema, chronic obstructive lung disease, or pulmonary fibrosis
- Family history of lung cancer
Tobacco use combined with one of these other risk factors can increase the risk of developing lung cancer in an exponential manner.