A risk
factor is anything that increases a person’s chance of getting a disease such
as cancer. Different cancers have different risk factors. Some risk factors,
like smoking, can be changed. Others, like a person’s age or family history,
can’t be changed.
But
having a risk factor, or even several, does not mean that you will get the
disease. And some people who get the disease may have few or no known risk
factors.
Several
risk factors can make you more likely to develop lung cancer. These
factors are related to the risk of lung cancer in general. It’s possible that some
of these might not apply to small cell lung cancer (SCLC).
Risk factors you can change
Tobacco smoke
Smoking is by far the leading risk factor
for lung cancer. About 80% of lung cancer deaths are thought to result from
smoking and this number is probably even higher for small cell lung cancer
(SCLC). It’s very rare for someone who has never smoked to have SCLC.
The
risk of lung cancer for smokers is many times higher than for non-smokers. The
longer you smoke and the more packs a day you smoke, the greater your risk.
Cigar smoking and pipe smoking are almost
as likely to cause lung cancer as cigarette smoking. Smoking low-tar or “light”
cigarettes increases lung cancer risk as much as regular cigarettes. Smoking
menthol cigarettes might increase the risk even more since the menthol may
allow smokers to inhale more deeply.
Secondhand smoke
If you
don’t smoke, breathing in the smoke of others (called secondhand smoke or environmental tobacco
smoke) can increase your risk of developing lung cancer. Secondhand smoke is
thought to cause more than 7,000 deaths from lung cancer each year.
If you
or someone you care about needs help quitting, see How To Quit Smoking or Smokeless Tobacco or
call the American Cancer Society at 1-800-227-2345
Exposure to radon
Radon
is a naturally occurring radioactive gas that results from the breakdown of
uranium in soil and rocks. You can’t see, taste, or smell it. According to the
US Environmental Protection Agency (EPA), radon is the second leading cause of
lung cancer in this country, and is the leading cause among non-smokers.
Outdoors,
there is so little radon that it is not likely to be dangerous. But indoors,
radon can be more concentrated. Breathing it in exposes your lungs to small
amounts of radiation. This may increase a person’s risk of lung cancer.
Homes
and other buildings in nearly any part of the United States can have high
indoor radon levels (especially in basements).
For
more information, see Radon and Cancer.
Exposure to asbestos
People
who work with asbestos (such as in mines, mills, textile plants, places where
insulation is used, and shipyards) are several times more likely to die of lung
cancer. Lung cancer risk is much greater in workers exposed to asbestos who
also smoke. It’s not clear how much low-level or short-term exposure to
asbestos might raise lung cancer risk.
People
exposed to large amounts of asbestos also have a greater risk of developing
mesothelioma, a type of cancer that starts in the pleura (the lining
surrounding the lungs). For more on this type of cancer, see Malignant Mesothelioma.
In
recent years, government regulations have greatly reduced the use of asbestos
in commercial and industrial products. It’s still present in many homes and
other older buildings, but it’s not usually considered harmful as long as it’s
not released into the air by deterioration, demolition, or renovation. For more
information, see Asbestos and Cancer Risk.
Exposure to other cancer-causing agents in the workplace
Other
carcinogens (cancer-causing agents) found in some workplaces that can increase
lung cancer risk include:
·
Radioactive ores such as uranium
·
Inhaled chemicals such as arsenic, beryllium, cadmium, silica, vinyl
chloride, nickel compounds, chromium compounds, coal products, mustard gas, and
chloromethyl ethers
The
government and industry have taken steps in recent years to help protect
workers from many of these exposures. But the dangers are still there, so if
you work around these agents, be careful to limit your exposure whenever
possible.
Taking certain dietary supplements
Studies
looking at the possible role of vitamin supplements in reducing lung cancer
risk have had disappointing results. In fact, 2 large studies found that
smokers who took beta carotene supplements actually had an increased risk of
lung cancer. The results of these studies suggest that smokers should avoid
taking beta carotene supplements.
Arsenic in drinking water
Studies
of people in parts of Southeast Asia and South America with high levels
of arsenic in their drinking water have
found a higher risk of lung cancer. In most of these studies, the levels of
arsenic in the water were many times higher than those typically seen in the
United States, even areas where arsenic levels are above normal. For most Americans
who are on public water systems, drinking water is not a major source of
arsenic.
Risk factors you cannot change
Previous radiation therapy to the lungs
People
who have had radiation therapy to the chest for other cancers are
at higher risk for lung cancer, particularly if they smoke. Examples include
people who have been treated for Hodgkin disease or women who get chest
radiation after a mastectomy for breast cancer. Women who have radiation therapy to the
breast after a lumpectomy do not appear to have a higher than expected risk of
lung cancer.
Air pollution
In
cities, air pollution (especially near heavily trafficked roads) appears to
raise the risk of lung cancer slightly. This risk is far less than the risk
caused by smoking, but some researchers estimate that worldwide about 5% of all
deaths from lung cancer may be due to outdoor air pollution.
Personal or family history of lung cancer
If you
have had lung cancer, you have a higher risk of developing another lung cancer.
Brothers,
sisters, and children of people who have had lung cancer may have a slightly
higher risk of lung cancer themselves, especially if the relative was diagnosed
at a younger age. It’s not clear how much of this risk might be due to shared
genes among family members and how much might be from shared household
exposures (such as tobacco smoke or radon).
Researchers
have found that genetics seems to play a role in some families with a strong
history of lung cancer. (See What Causes Lung Cancer?).
Factors with uncertain or unproven effects on lung cancer risk
Smoking marijuana
There
are reasons to think smoking marijuana might increase lung cancer risk.
·
Marijuana smoke contains tar and many of same cancer-causing
substances that are in tobacco smoke. (Tar is the sticky, solid material that
remains after burning, which is thought to contain most of the harmful
substances in smoke.)
·
Marijuana cigarettes (joints) are typically smoked all the way
to the end, where tar content is the highest.
·
Marijuana is inhaled very deeply and the smoke is held in the
lungs for a long time, which gives any cancer-causing substances more
opportunity to deposit in the lungs.
·
Because marijuana is still illegal in many places, it may not be
possible to control what other substances it might contain.
Those
who use marijuana tend to smoke fewer marijuana cigarettes in a day or week
than the amount of tobacco consumed by cigarette smokers. The lesser amount
smoked would make it harder to see an impact on lung cancer risk.
It’s
been hard to study whether there is a link between marijuana and lung cancer
because marijuana has been illegal in many places for so long, and it’s not
easy to gather information about the use of illegal drugs. Also, in studies
that have looked at past marijuana use in people who had lung cancer, most of
the marijuana smokers also smoked cigarettes. This can make it hard to know how
much any increased risk is from tobacco and how much might be from marijuana.
More research is needed to know the cancer risks from smoking marijuana.
E-cigarettes
E-cigarettes are a type of electronic
nicotine delivery system. They do not contain any tobacco but the Food and Drug
Administration (FDA) classifies them as “tobacco” products. E-cigarettes are
fairly new and more research is needed to know what the long-term effects might
be, including the risk of developing lung cancer.
Talc and talcum powder
Talc is
a mineral that in its natural form may contain asbestos. Some studies have
suggested that talc miners and people who operate talc mills might have a
higher risk of lung cancer and other respiratory diseases because of their
exposure to industrial grade talc. But other studies have not found an increase
in lung cancer rate.
Talcum powder is made from talc. The use
of cosmetic talcum powder has not been found to increase lung cancer risk.
Our team is made up of doctors and oncology certified
nurses with deep knowledge of cancer care as well as journalists, editors, and
translators with extensive experience in medical writing.
Last
Medical Review: October 1, 2019 Last Revised:
October 1, 2019
American
Cancer Society medical information is copyrighted material. For reprint
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