Lung Cancer (small cell) Overview

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Causes, Risk Factors, and Prevention TOPICS

What are the risk factors for small cell lung cancer?

A risk factor is anything that affects 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 risk factors, does not mean that you will get the disease. And some people who get the disease may have few or no known risk factors. Even if a person with lung cancer has a risk factor, it is often very hard to know how much it may have contributed to the cancer.

Several risk factors can make you more likely to get lung cancer.

Tobacco smoke

Smoking is by far the leading risk factor for lung cancer. Tobacco smoke causes at least 8 out of 10 deaths from lung cancer. This number is probably even higher for small cell lung cancer. It is very rare for someone who has never smoked to have small cell lung cancer. The longer a person has been smoking and the more packs per day smoked, the greater the risk.

Cigar and pipe smoking are almost as likely to cause lung cancer as is cigarette smoking. And smoking low tar or “light” cigarettes increases lung cancer risk as much as regular cigarettes. There is concern that menthol cigarettes may increase the risk even more since the menthol allows smokers to inhale more deeply.

Stopping smoking at any age may lower your risk of lung cancer. For help quitting, see our Guide to Quitting Smoking or call us at 1-800-227-2345.

Secondhand smoke: People who don’t smoke but who breathe the smoke of others may also be at a higher risk for lung cancer. Non-smokers who live with a smoker, for instance, have about a 20% to 30% greater risk of developing lung cancer. Non-smokers exposed to tobacco smoke in the workplace are also more likely to get lung cancer. Secondhand smoke is thought to cause more than 3,000 deaths from lung cancer each year.


Radon is a radioactive gas made by the normal breakdown of uranium in soil and rocks. Uranium is found at higher levels in the soil in some parts of the United States. Radon can’t be seen, tasted, or smelled. It can build up indoors and create a possible risk for cancer. The lung cancer risk from radon is much lower than that from tobacco smoke. But the risk is much higher in people who smoke than in those who don’t.

State and local offices of the EPA (Environmental Protection Agency) can give you information on how to test for radon in the home. To learn more, see our document Radon.


Asbestos exposure is another risk factor for lung cancer. People who work with asbestos have a higher risk of getting lung cancer. If they also smoke, the risk is greatly increased. Both smokers and non-smokers exposed to asbestos also have a greater risk of getting a type of cancer called mesothelioma, which starts in the lining of the lungs. This type of cancer is discussed in our document Malignant Mesothelioma.

Although asbestos was used for many years, the government has now nearly stopped its use in the workplace and in home products. It is still present in many buildings, but it is not thought to be harmful as long as it is not released into the air. To learn more, see our document, Asbestos.

Other cancer-causing things in the workplace

Other things in some workplaces that can increase lung cancer risk include:

  • Radioactive ores, such as uranium
  • Inhaled chemicals or minerals like arsenic, beryllium, cadmium, silica, vinyl chloride, nickel compounds, chromium compounds, coal products, mustard gas, and chloromethyl ethers
  • Diesel exhaust

The government and industry have taken major steps in recent years to help protect workers. But the dangers are still there. If you work around any of these, you should be very careful to limit how much you are exposed.

Air pollution

In cities, air pollution (such as from heavy traffic) may slightly increase the risk of lung cancer. But the risk is still far less than that caused by smoking. Worldwide, about 5% of all deaths from lung cancer may be due to outdoor air pollution.

Radiation treatment to the lungs

People who have had radiation to the chest to treat other cancers are at higher risk for lung cancer, especially if they smoke. Women who have radiation to the breast after a lumpectomy for breast cancer do not appear to have a higher risk of lung cancer.

Arsenic in drinking water

High levels of arsenic in drinking water, such as is seen in parts of Southeast Asia and South America, may increase the risk of lung cancer. The effect is even greater for smokers. This is less of a problem in the United States.

Personal and family history of lung cancer

If you have had lung cancer, you have a higher risk of getting another lung cancer. Brothers, sisters, and children of people who have had lung cancer may have a slightly higher risk themselves, especially if the family got cancer at a younger age. It is not clear how much of this might be due to shared genes among family members and how much might be from shared household exposures (such as tobacco smoke or radon).

Certain vitamins

Two large studies have 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 not take beta carotene supplements.

Last Medical Review: 09/09/2013
Last Revised: 02/11/2014