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Cancer prevention is action taken to lower the chance of getting cancer. By preventing cancer, the number of new cases of cancer in a group or population is lowered. Hopefully, this will lower the number of deaths caused by cancer.
To prevent new cancers from starting, scientists look at risk factors and protective factors. Anything that increases your chance of developing cancer is called a cancer risk factor; anything that decreases your chance of developing cancer is called a cancer protective factor.
Some risk factors for cancer can be avoided, but many cannot. For example, both smoking and inheriting certain genes are risk factors for some types of cancer, but only smoking can be avoided. Regular exercise and a healthy diet may be protective factors for some types of cancer. Avoiding risk factors and increasing protective factors may lower your risk but it does not mean that you will not get cancer.
Different ways to prevent cancer are being studied, including:
Lung cancer is a disease in which malignant (cancer) cells form in the tissues of the lung.
The lungs are a pair of cone-shaped breathing organs in the chest. The lungs bring oxygen into the body as you breathe in. They release carbon dioxide, a waste product of the body's cells, as you breathe out. Each lung has sections called lobes. The left lung has two lobes. The right lung is slightly larger, and has three lobes. A thin membrane called the pleura surrounds the lungs. Two tubes called bronchi lead from the trachea (windpipe) to the right and left lungs. The bronchi are sometimes also involved in lung cancer. Tiny air sacs called alveoli and small tubes called bronchioles make up the inside of the lungs.
Anatomy of the respiratory system, showing the trachea and both lungs and their lobes and airways. Lymph nodes and the diaphragm are also shown. Oxygen is inhaled into the lungs and passes through the thin membranes of the alveoli and into the bloodstream (see inset).
There are two types of lung cancer: small cell lung cancer and non-small cell lung cancer.
See the following PDQ summaries for more information about lung cancer:
Lung cancer is the leading cause of cancer death in both men and women.
More people die from lung cancer than from any other type of cancer. Lung cancer is the second most common cancer in the United States, after skin cancer.
The number of new cases and deaths from lung cancer is highest in black men.
Avoiding risk factors and increasing protective factors may help prevent lung cancer.
Avoiding cancer risk factors may help prevent certain cancers. Risk factors include smoking, being overweight, and not getting enough exercise. Increasing protective factors such as quitting smoking, eating a healthy diet, and exercising may also help prevent some cancers. Talk to your doctor or other health care professional about how you might lower your risk of cancer.
The following are risk factors for lung cancer:
Cigarette, cigar, and pipe smoking
Tobacco smoking is the most important risk factor for lung cancer. Cigarette, cigar, and pipe smoking all increase the risk of lung cancer. Tobacco smoking causes about 9 out of 10 cases of lung cancer in men and about 8 out of 10 cases of lung cancer in women.
Studies have shown that smoking low tar or low nicotine cigarettes does not lower the risk of lung cancer.
Studies also show that the risk of lung cancer from smoking cigarettes increases with the number of cigarettes smoked per day and the number of years smoked. People who smoke have about 20 times the risk of lung cancer compared to those who do not smoke.
Being exposed to secondhand tobacco smoke is also a risk factor for lung cancer. Secondhand smoke is the smoke that comes from a burning cigarette or other tobacco product, or that is exhaled by smokers. People who inhale secondhand smoke are exposed to the same cancer -causing agents as smokers, although in smaller amounts. Inhaling secondhand smoke is called involuntary or passive smoking.
Having a family history of lung cancer is a risk factor for lung cancer. People with a relative who has had lung cancer may be twice as likely to have lung cancer as people who do not have a relative who has had lung cancer. Because cigarette smoking tends to run in families and family members are exposed to secondhand smoke, it is hard to know whether the increased risk of lung cancer is from the family history of lung cancer or from being exposed to cigarette smoke.
Environmental risk factors
Studies show that high levels of radon gas inside homes and other buildings increase the number of new cases of lung cancer and the number of deaths caused by lung cancer. The risk of lung cancer is higher in smokers exposed to radon than in nonsmokers exposed to radon. In people who have never smoked, about 30% of deaths caused by lung cancer have been linked to being exposed to radon.
These substances can cause lung cancer in people who are exposed to them in the workplace and have never smoked. The risk of lung cancer is higher in people who are exposed and also smoke.
Beta carotene supplements in heavy smokers
Taking beta carotene supplements (pills) increases the risk of lung cancer, especially in smokers who smoke one or more packs a day. The risk is higher in smokers who have at least one alcoholic drink every day.
It is not clear if the following increases the risk of lung cancer:
Being infected with the human immunodeficiency virus (HIV), the cause of acquired immunodeficiency syndrome (AIDS), is linked with a higher risk of lung cancer. People infected with HIV may have more than twice the risk of lung cancer than those who are not infected. Since smoking rates are higher in those infected with HIV than in those not infected, it is hard to know whether the increased risk of lung cancer is from the HIV infection or from being exposed to cigarette smoke.
The following are protective factors for lung cancer:
The best way to prevent lung cancer is to not smoke.
Smokers can decrease their risk of lung cancer by quitting. In smokers who have been treated for lung cancer, quitting smoking lowers the risk of new lung cancers. Counseling, the use of nicotine replacement products, and antidepressant therapy have helped smokers quit for good.
In a person who has quit smoking, the chance of preventing lung cancer depends on how many years and how much the person smoked and the length of time since quitting. After a person has quit smoking for 10 years, the risk of lung cancer decreases 30% to 50%.
See the following for more information on quitting smoking:
Lower exposure to workplace risk factors
Laws that protect workers from being exposed to cancer-causing substances, such as asbestos, arsenic, nickel, and chromium, may help lower their risk of developing lung cancer. Laws that prevent smoking in the workplace help lower the risk of lung cancer caused by secondhand smoke.
Lower exposure to radon
Lowering radon levels may lower the risk of lung cancer, especially among cigarette smokers. High levels of radon in homes may be reduced by taking steps to prevent radon leakage, such as sealing basements.
It is not clear if the following decrease the risk of lung cancer:
Some studies show that people who eat high amounts of fruits or vegetables have a lower risk of lung cancer than those who eat low amounts. However, since smokers tend to have less healthy diets than nonsmokers, it is hard to know whether the decreased risk is from having a healthy diet or from not smoking.
Some studies show that people who are physically active have a lower risk of lung cancer than people who are not. However, since smokers tend to have different levels of physical activity than nonsmokers, it is hard to know if physical activity affects the risk of lung cancer.
The following do not decrease the risk of lung cancer:
Beta carotene supplements in nonsmokers
Studies of nonsmokers show that taking beta carotene supplements does not lower their risk of lung cancer.
Vitamin E supplements
Studies show that taking vitamin E supplements does not affect the risk of lung cancer.
Cancer prevention clinical trials are used to study ways to prevent cancer.
Cancer prevention clinical trials are used to study ways to lower the risk of developing certain types of cancer. Some cancer prevention trials are conducted with healthy people who have not had cancer but who have an increased risk for cancer. Other prevention trials are conducted with people who have had cancer and are trying to prevent another cancer of the same type or to lower their chance of developing a new type of cancer. Other trials are done with healthy volunteers who are not known to have any risk factors for cancer.
The purpose of some cancer prevention clinical trials is to find out whether actions people take can prevent cancer. These may include eating fruits and vegetables, exercising, quitting smoking, or taking certain medicines, vitamins, minerals, or food supplements.
New ways to prevent lung cancer are being studied in clinical trials.
Clinical trials are taking place in many parts of the country. Information about clinical trials can be found in the Clinical Trials section of the NCI Web site. Check NCI's list of cancer clinical trials for prevention trials for non-small cell lung cancer and small cell lung cancer that are now accepting patients. These include trials for quitting smoking.
The PDQ cancer information summaries are reviewed regularly and updated as new information becomes available. This section describes the latest changes made to this summary as of the date above.
Editorial changes were made to this summary.
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PDQ is a comprehensive cancer database available on NCI's Web site.
PDQ is the National Cancer Institute's (NCI's) comprehensive cancer information database. Most of the information contained in PDQ is available online at NCI's Web site. PDQ is provided as a service of the NCI. The NCI is part of the National Institutes of Health, the federal government's focal point for biomedical research.
PDQ contains cancer information summaries.
The PDQ database contains summaries of the latest published information on cancer prevention, detection, genetics, treatment, supportive care, and complementary and alternative medicine. Most summaries are available in two versions. The health professional versions provide detailed information written in technical language. The patient versions are written in easy-to-understand, nontechnical language. Both versions provide current and accurate cancer information.
Images in the PDQ summaries are used with permission of the author(s), artist, and/or publisher for use within the PDQ summaries only. Permission to use images outside the context of PDQ information must be obtained from the owner(s) and cannot be granted by the National Cancer Institute. Information about using the illustrations in the PDQ summaries, along with many other cancer-related images, are available in Visuals Online, a collection of over 2,000 scientific images.
The PDQ cancer information summaries are developed by cancer experts and reviewed regularly.
Editorial Boards made up of experts in oncology and related specialties are responsible for writing and maintaining the cancer information summaries. The summaries are reviewed regularly and changes are made as new information becomes available. The date on each summary ("Date Last Modified") indicates the time of the most recent change.
PDQ also contains information on clinical trials.
A clinical trial is a study to answer a scientific question, such as whether a certain drug or nutrient can prevent cancer. Trials are based on past studies and what has been learned in the laboratory. Each trial answers certain scientific questions in order to find new and better ways to help cancer patients and those who are at risk for cancer. During prevention clinical trials, information is collected about the effects of a new prevention method and how well it works. If a clinical trial shows that a new method is better than one currently being used, the new method may become "standard." People who are at high risk for a certain type of cancer may want to think about taking part in a clinical trial.
Listings of clinical trials are included in PDQ and are available online at NCI's Web site. Descriptions of the trials are available in health professional and patient versions. Many cancer doctors who take part in clinical trials are also listed in PDQ. For more information, call the Cancer Information Service 1-800-4-CANCER (1-800-422-6237).
Last Revised: 2012-05-24
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