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Risk Factors

Research has found several risk factors for lung cancer. A "risk factor" is anything that changes risk of getting a disease. Different risk factors change risk by different amounts.

The risk factors for lung cancer include

• smoking and being around others' smoke
• things around us at home or work (such as radon gas)
• personal traits (such as having a family history of lung cancer)

Smoking and Secondhand Smoke
Cigarette smoking causes lung cancer. In fact, smoking tobacco is the major risk factor for lung cancer. In the United States, about 90% of lung cancer deaths in men and almost 80% of lung cancer deaths in women are due to smoking. People who smoke are 10 to 20 times more likely to get lung cancer or die from lung cancer than people who do not smoke. The longer a person smokes and the more cigarettes smoked each day the more risk goes up. ^{1, 2, 3, 4, 5, 6, 7, 8}

People who quit smoking have a lower risk of lung cancer than if they had continued to smoke, but their risk is higher than people who never smoked.⁷ As more people quit smoking, lung cancer rates will continue to fall, the percentage of lung cancers that occur in smokers will decrease, and the percentage of lung cancers that occur in people who have quit will rise.

Smoking also causes cancer of the voicebox (larynx,) mouth and throat, esophagus, bladder, kidney, pancreas, cervix, and stomach. More information about cigarette smoking and lung cancer is available in CDC's Smoking and Tobacco Use Fact Sheets, the Surgeon General's Report 2004, and the NCI Cigarette Smoking and Cancer Questions and Answers.

Using cigars or pipes also increases risk for lung cancer, but not as much as smoking cigarettes. For more information, visit the NCI Questions and Answers About Cigar Smoking and Cancer. ^{2, 3, 4, 8, 9, 10, 11}

Smoke from other people's cigarettes ("secondhand" smoke) causes lung cancer as well. Secondhand smoke contains more than 4,000 chemicals, more than 50 of which cause cancer in people or animals. Every year, about 3,000 nonsmokers die from lung cancer due to secondhand smoke. ^{5, 12, 13, 14, 15, 16}

For more information, visit Secondhand Smoke.

Things That May Cause Cancer at Home and Work
Several things may cause cancer (carcinogens) in the workplace or even in the home. For example, radon gas causes lung cancer and is sometimes found in people's homes. Radon is an odorless, colorless gas that comes from rocks and dirt and can get trapped in houses and buildings. Examples of substances found at some workplaces that increase risk include asbestos, arsenic, and some forms of silica and chromium. For many of these substances, the risk of getting lung cancer is even higher for those who also smoke. ^{2, 3, 6, 17, 18, 19} Other substances may increase lung cancer risk as well.

For more information on carcinogens and cancer in the workplace, visit the links below.

• Agency for Toxic Substances and Disease Registry ToxFAQs™
• National Toxicology Program's 11th Report on Carcinogens
• National Institute for Occupational Safety and Health

Family History
Risk of lung cancer may be higher if a person's parents, siblings (brother or sister), or children have had lung cancer. This increased risk could come from one or more things. They may share behaviors, like smoking. They may live in the same place where there are carcinogens such as radon. They may have inherited increased risk in their genes. ^{20, 21, 22, 23}

For more information, visit the CDC's National Office of Public Health Genomics.

Diet
Scientists are studying many different foods to see how they may change the risk of getting lung cancer. However, any effect diet may have on lung cancer risk is small compared with the risk from smoking. Eating a lot of fat and cholesterol might increase risk of lung cancer. Drinking a lot of alcohol may raise risk as well. However, it's hard to tell how much of the risk in people who drink is actually due to tobacco smoke, since many people both smoke and drink.

Some foods may actually help prevent lung cancer. Diets high in fruits and vegetables likely decrease cancer risk. Diets high in vitamin C, vitamin E, or selenium might also help protect against lung cancer. The effect of eating foods with carotenoids, like beta-carotene, on lung cancer risk is currently uncertain. Carotenoids can be found in carrots, sweet potatoes, and some green vegetables. Eating these foods may lower chances of lung cancer. Taking beta-carotene supplements (pills) is not recommended, however, since it may actually increase risk in some smokers. ^{6, 8, 24, 25, 26}

For more information, visit the National Cancer Institute's Diet and Cancer.

References

1. American Cancer Society. Cancer Facts and Figures 2005 (PDF-1.7MB).*
2. International Agency for Research on Cancer (IARC). IARC Monographs on the Evaluation of Carcinogenic Risks to Humans and their Supplements: A complete list. Tobacco Smoking. Monograph Volume 38 (1986).
3. International Agency for Research on Cancer (IARC). IARC Monographs on the Evaluation of Carcinogenic Risks to Humans and their Supplements: A complete list. Tobacco Smoking and Tobacco Smoke Volume 83 (2002). (PDF 48 Kb)*
4. U.S. Department of Health, Education and Welfare. Smoking and Health: Report of the Advisory Committee to the Surgeon General of the Public Health Service (1964).
5. U.S. Department of Health and Human Services. Women and Smoking: A Report of the Surgeon General (2001).
6. Alberg AJ, Samet JM. Epidemiology of lung cancer.* Chest 2003;123:21S–49S.
7. U.S. Department of Health and Human Services. Health Consequences of Smoking: A Report of the Surgeon General (2004).
8. Institute of Medicine (IOM) National Cancer Policy Board. Fulfilling the Potential of Cancer Prevention and Early Detection. Curry SJ, Byers T, Hewitt M (eds). National Academies Press. Washington, D.C., 2003.
9. National Institutes of Health, National Cancer Institute Smoking. Tobacco control monograph 9: Cigars; health effects and trends. NIH Publication No. 98-4302. Bethesda, MD: U.S. Department of Health and Human Services, 1998.
10. Boffetta P, Pershagen G, Jockel KH, et al. Cigar and pipe smoking and lung cancer risk: A multicenter study from Europe. Journal of the National Cancer Institute 1999; 91:697-701.
11. U.S. Department of Health and Human Services. Smoking and Health: A Report of the Surgeon General (1979).
12. U.S. Department of Health and Human Services. The Health Consequences of Involuntary Smoking: A Report of the Surgeon General (1986).
13. National Institutes of Health (NIH), National Cancer Institute. Smoking and Tobacco Control Monograph 10 (1999): Health Effects of Exposure to Environmental Tobacco Smoke.
14. National Research Council (NRC), Committee on Passive Smoking. Environmental Tobacco Smoke: Measuring Exposures and Assessing Health Effects (1986).*
15. U.S. Environmental Protection Agency. Respiratory Health Effects of Passive Smoking. (1992).
16. International Agency for Research on Cancer (IARC). IARC Monographs on the Evaluation of Carcinogenic Risks to Humans and their Supplements: A complete list. Involuntary Smoking Volume 83 (2002). (PDF 45 Kb)*
17. International Agency for Research on Cancer (IARC). IARC Monographs on the Evaluation of Carcinogenic Risks to Humans and their Supplements: A complete list. Overall Evaluations of Carcinogenicity: An Updating of IARC Monographs Volumes 1 to 42. (1987). (PDF 1 Mb)*
18. U.S. Department of Health and Human Services, Public Health Service, National Toxicology Program. Report on Carcinogens, Eleventh Edition. (2004).
19. International Agency for Research on Cancer (IARC). IARC Monographs on the Evaluation of Carcinogenic Risks to Humans and their Supplements: A complete list. Some Metals and Metallic Compounds (PDF 28Kb)*: Arsenic and Arsenic Compounds. (PDF 1Mb)* Volume 23 (1980).
20. Etzel CJ, Amos CI, Spitz MR. Risk for smoking-related cancer among relatives of lung cancer patients.* Cancer Research 2003;63:8531–8535.
21. Brownson RC, Alavanja MCR, Caporaso N, Berger E, Change JC. Family history of cancer and risk of lung cancer in lifetime non-smokers and long-term ex-smokers. International Journal of Epidemiology 1997;26:256–263.
22. Bromen K, Pohlabeln H, Jahn I, Ahrens W, Jockel KH. Aggregation of lung cancer in families: Results from a population-based case-control study in Germany. American Journal of Epidemiology 2000;152:497–505.
23. Mayne ST, Buenconsejo J, Janerich DT. Familial cancer history and lung cancer risk in United States nonsmoking men and women. Cancer Epidemiology, Biomarkers & Prevention 1999;8:1065–1069.
24. World Cancer Research Fund/American Institute for Cancer Research. Food, Nutrition and the Prevention of Cancer: A global perspective.* Washington, D.C.: American Institute for Cancer Research, 1997.
25. Institute of Medicine (IOM), Food and Nutrition Board, Subcommittees on Upper Reference Levels of Nutrients and Interpretation and Uses of Dietary Reference Intakes, and the Standing Committee on the Scientific Evaluation of Dietary Reference Intakes. A Report of the Panel on Dietary Antioxidants and Related Compounds: Dietary Reference Intakes for Vitamin C, Vitamin E, Selenium and Carotenoids (2000).*
26. Institute of Medicine (IOM), Food and Nutrition Board, Committee on Examination of the Evolving Sciences for Dietary Supplements. Evolution of Evidence for Selected Nutrient and Disease Relationships (2002).*

Please note: Some of these publications are available for download only as *.pdf files. These files require Adobe Acrobat Reader in order to be viewed. Please review the information on downloading and using Acrobat Reader software.

*Links to non-Federal organizations found at this site are provided solely as a service to our users. These links do not constitute an endorsement of these organizations or their programs by CDC or the Federal Government, and none should be inferred. CDC is not responsible for the content of the individual organization Web pages found at these links.