During a lifetime, the human body is exposed to many things—including radiation, certain chemicals (i.e. tobacco) and infections—that can damage its cells. This sort of damage increases the likelihood that cells will grow and divide out of control to form a tumour. The immune system, which gets rid of abnormal cells, becomes less efficient as people grow older. Over the years, little bits of wear and tear that did not cause a problem at first can add up. This is one reason that the odds of getting cancer of any kind increases with age. Some people may also be genetically predisposed, so that their cells are more susceptible to damage.

Common Causes 

Other Causes 

Personal History of Cancer or Other Lung Diseases

Lung cancer is more common in people who have been previously diagnosed with cancers of the mouth or throat. Damage from previous lung diseases or conditions—for example, chronic obstructive pulmonary disease (COPD, which involves emphysema and chronic bronchitis), pneumonia, and tuberculosis—also increase the risk of lung cancer.

Family History

Cancer cells contain mutations (that is, genetic changes) that make them behave abnormally. Some mutations can be passed down from parent to child. So people who have a family history of lung cancer may be predisposed to developing cancer themselves. This increase could also be the result of shared behaviours (for example, smoking) or a shared environment that exposes them to carcinogens.

Pollutants in the Environment

Exposure to certain pollutants and chemicals at home, in the workplace, and in the environment can increase the risk of lung cancer. Air pollution from motor vehicles, factories, and power plants contain microscopic particles, nitrogen oxides, diesel exhaust, benzene, and polycyclic aromatic hydrocarbons. Some people are exposed to asbestos, chromium, nickel, silica, and arsenic at their workplace. Other chemicals known to contribute to lung cancer risk include bis(chloromethyl) ether, vinyl chloride, uranium, and coal tar products.

For more information on asbestos, visit;
“Asbestos and Cancer - Canadian Cancer Society.”,