5 Causes of Lung Cancer in Non-Smokers
Medical Author: Melissa Conrad Stoppler, MD
Medical Editor: Jay W. Marks, MD
While cigarette smoking is
an undisputed cause of lung
cancer, not all cases
of lung cancer occur in smokers or former smokers. Each year, over 170,000
Americans develop lung cancer, and approximately ten per cent of lung cancers,
or 17,000 cases, occur in non-smokers. Although not every non-smoker suffering
from lung cancer will have an identifiable risk factor for development of the disease, a number of conditions and circumstances have been identified that will
increase a non-smoker's chance of developing lung cancer.
- Passive smoking,
or the inhalation of tobacco smoke from other smokers sharing living or
working quarters, is an established risk factor for the development of lung
cancer. Non-smokers who reside with a smoker have a 24% increase in risk for
developing lung cancer when compared with other non-smokers. Each year, up
to 3,000 lung cancer deaths are estimated to occur in the U.S. that are
attributable to passive smoking.
- Radon gas, a naturally-occurring gas that forms when uranium decays,
is another known cause of lung cancer. An estimated 12% of total lung cancer
deaths in both smokers and non-smokers, or 15,000 to 22,000 lung cancer-related
deaths annually in the U.S, are believed to be at least partially related to
radon gas exposure.
Those who do smoke and are exposed to radon have an even greater risk of
developing lung cancer than non-smokers who are exposed to radon gas. Radon
gas can travel up through soil and enter homes through gaps in the
foundation, pipes, drains, or other openings. The U.S. Environmental
Protection Agency estimates that one out of every 15 homes in the U.S.
contains dangerous levels of radon gas. Radon gas is invisible and odorless
but can be detected with simple test kits.
- Asbestos is a
compound that was widely used in the past as both thermal and acoustic
insulation material. Microscopic fibers of asbestos break loose from the
insulation material and are released into the air where they can be inhaled into
the lungs. Asbestos fibers can persist for a lifetime in lung tissue following exposure to asbestos. Both lung cancer and a type of cancer
known as mesothelioma are
associated with exposure to asbestos. Cigarette smoking drastically
increases the chance of developing an asbestos-related lung cancer among
workers exposed to asbestos; nevertheless, asbestos workers who do not smoke
have a five fold greater risk of developing lung cancer than other
non-smokers. Today, asbestos use is limited or banned in many countries
including the Unites States.
- Heredity, since all
smokers do not eventually develop lung cancer,
it is likely that other factors, such as individual genetic susceptibility, may play a role in the
causation of lung cancer. Numerous studies have shown that lung cancer is more
likely to occur in both smoking and non-smoking relatives of those who have had
lung cancer than in the general population.
- Air pollution from vehicles,
industry, and power plants, can raise the likelihood of developing lung cancer
in exposed individuals. It has been estimated that up to 2,000 lung cancer
deaths per year may be attributable to breathing polluted air, and many experts believe that prolonged exposure to
highly polluted air can carry a risk for the development of lung cancer similar
to that of passive smoking.
REFERENCE: National Institutes of Health. New Early Detection Studies of Lung Cancer in Non-Smokers Launched Today. News Release, May 4, 2009.Last Editorial Review: 10/18/2011