Cancer Institute A national cancer institute
designated cancer center

The Genetics of Lung Cancer

The majority of lung cancers (90 percent) are due to cigarette smoking. A number of diverse genetic abnormalities have been identified in lung cancer cells. Some of these genetic abnormalities may be causal (i.e., responsible for initiating the development of cancer), while others may instead indicate the progression of the cancer.

Not everyone who smokes will develop lung cancer. Studies have identified that normal genetic variations in the population, known as "polymorphisms," may make some individuals more likely to develop lung cancer if they smoke than other smokers (without the polymorphism).

Genetic polymorphisms may also be important for nonsmokers. About one in six nonsmokers are exposed to tobacco smoke from smokers in their own homes. Certain genetic polymorphisms have been found to be associated with a statistically greater risk of lung cancer development, even in a person who has never smoked.

This may explain why relatives of persons with lung cancer, regardless of whether they smoke or not, have an increased chance (about double the general population) to develop lung cancer. Additional studies are needed to better understand these gene-environment interactions.

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