Home > Patients & Visitors > Health Library > Cigarette Smoking: Health Risks and How to Quit (PDQ®): Prevention - Patient Information [NCI]
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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.
Smoking is the leading cause of cancer in the United States.
Smoking increases the risk of many types of cancer. These include:
A smoker's risk of cancer can be 2 to 10 times higher than it is for a person who never smoked. This depends on how much and how long the person smoked.
Lung cancer is the leading cause of cancer death in both men and women. In 2014, about 19% of adult men and about 15% of adult women were smokers. In the last 30 years, the total number of smokers has decreased, especially among men. Since the 1980s, deaths caused by lung cancer in men have been decreasing.
From 2011 to 2014, smoking decreased among middle school and high school students. Raising the legal age to buy and use tobacco products is being studied as a way to prevent or decrease smoking and other tobacco use among young people.
Smoking causes many other health problems.
Smoking is linked with many diseases besides cancer. These include:
Other health problems that may be linked to smoking are:
Smoking during pregnancy may cause problems such as slow growth of the fetus and low birth weight.
Being exposed to secondhand smoke increases the risk of cancer and other diseases.
Smoking can also affect the health of nonsmokers. Smoke that comes from the burning of a tobacco product or smoke that is exhaled by smokers is called secondhand smoke. Inhaling secondhand smoke is called involuntary or passive smoking.
The same cancer-causing chemicals inhaled by tobacco smokers are inhaled in lower amounts by people exposed to secondhand tobacco smoke. Nonsmokers who are exposed to secondhand smoke have a higher risk of lung cancer and coronary heart disease. Children exposed to tobacco smoke have higher risks of the following:
Quitting smoking improves health in smokers of all ages.
The risk of most health problems from smoking, including cancer and heart and lung disease, can be lowered by stopping smoking. People of all ages can improve their health if they quit smoking. Quitting at a younger age will improve a person's health even more. People who quit smoking cut their risk of lung cancer by 30% to 50% after 10 years compared to people who keep smoking, and they cut their risk of cancer of the mouth or esophagus in half within 5 years after quitting.
The damage caused by smoking is even worse for people who have had cancer. They have an increased risk of cancer recurrence, new cancers, and long-term side effects from cancer treatment. Quitting smoking and stopping other unhealthy behaviors can improve long-term health and quality of life.
The Public Health Service has a set of guidelines called Treating Tobacco Use and Dependence. It asks health care professionals to talk to their patients about the health problems caused by smoking and the importance of quitting smoking.
Different ways to quit smoking have been studied. The following are the most common methods used to help smokers quit:
People who have even a short counseling session with a health care professional are more likely to quit smoking. Your doctor or other health care professional may take the following steps to help you quit:
The Lung Health Study found that heavy smokers who received counseling from a doctor, took part in group sessions with other smokers to change their behavior, and used nicotine gum were more likely to quit smoking compared with smokers who did not receive counseling from a doctor, take part in group sessions, and use nicotine gum. They also had a lower risk of lung cancer, other cancers, heart disease, and respiratory disease.
Childhood cancer survivors who smoke may be more likely to quit when they take part in programs that use peer-counseling. In these programs, childhood cancer survivors are trained in ways to give support to other childhood cancer survivors who smoke and want to quit. More people quit smoking with peer-counseling than with self-help programs. If you are a childhood cancer survivor and you smoke, talk to your doctor about peer-counseling programs.
Treatment with drugs is also used to help people quit smoking. These include nicotine replacement products and non-nicotine medicines. People who use any type of drug treatment are more likely to quit smoking after 6 months than those who use a placebo or no drug treatment at all.
Nicotine replacement products have nicotine in them. You slowly reduce the use of the nicotine product in order to reduce the amount of nicotine you take in. Using a nicotine replacement product can help break the addiction to nicotine. It lessens the side effects of nicotine withdrawal, such as feeling depressed or nervous, having trouble thinking clearly, or having trouble sleeping. Nicotine replacement products, used alone or in combination, have been shown to help people quit smoking. These include:
Nicotine replacement products can cause problems in some people, especially:
Other medicines that do not have nicotine in them are used to help people quit smoking. These include:
These medicines lessen nicotine craving and nicotine withdrawal symptoms.
It is important to know that bupropion and varenicline may cause serious psychiatric problems. Symptoms include:
Varenicline may also cause serious heart problems.
Before starting to take bupropion or varenicline, talk to your doctor about the important health benefits of quitting smoking and the small but serious risk of problems with the use of these drugs.
When smokers do not quit smoking completely but smoke fewer cigarettes (smoking reduction) they may still benefit. The more you smoke, the higher your risk of lung cancer and other cancers related to smoking. Studies show that smokers who cut back are more likely to stop smoking in the future.
Smoking less is not as helpful as quitting smoking altogether, and is harmful if you inhale more deeply or smoke more of each cigarette to try to control nicotine cravings. In smokers who do not plan to quit smoking completely, nicotine replacement products have been shown to help them cut down the number of cigarettes they smoke, but this effect does not appear to last over time.
The following resources can help you quit smoking:
There are new and different types of tobacco and nicotine products.
The use of new or different types of tobacco products and devices that deliver nicotine is increasing rapidly in the United States, especially the use of electronic-cigarettes (e-cigarettes) by adults and adolescents.
Examples of new and different tobacco and nicotine products and devices include the following:
More studies are needed to understand the risks and benefits of using these products.
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 help smokers quit are being studied in clinical trials.
Information about clinical trials supported by NCI can be found on NCI's clinical trials search webpage. Clinical trials supported by other organizations can be found on the ClinicalTrials.gov website.
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Purpose of This Summary
This PDQ cancer information summary has current information about the prevention and cessation of cigarette smoking and the control of tobacco use. It is meant to inform and help patients, families, and caregivers. It does not give formal guidelines or recommendations for making decisions about health care.
Reviewers and Updates
Editorial Boards write the PDQ cancer information summaries and keep them up to date. These Boards are made up of experts in cancer treatment and other specialties related to cancer. The summaries are reviewed regularly and changes are made when there is new information. The date on each summary ("Updated") is the date of the most recent change.
The information in this patient summary was taken from the health professional version, which is reviewed regularly and updated as needed, by the PDQ Screening and Prevention Editorial Board.
Clinical Trial Information
A clinical trial is a study to answer a scientific question, such as whether one treatment is better than another. 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. During treatment clinical trials, information is collected about the effects of a new treatment and how well it works. If a clinical trial shows that a new treatment is better than one currently being used, the new treatment may become "standard." Patients may want to think about taking part in a clinical trial. Some clinical trials are open only to patients who have not started treatment.
Clinical trials can be found online at NCI's website. For more information, call the Cancer Information Service (CIS), NCI's contact center, at 1-800-4-CANCER (1-800-422-6237).
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The best way to cite this PDQ summary is:
PDQ® Screening and Prevention Editorial Board. PDQ Cigarette Smoking. Bethesda, MD: National Cancer Institute. Updated <MM/DD/YYYY>. Available at: https://www.cancer.gov/about-cancer/causes-prevention/risk/tobacco/quit-smoking-pdq. Accessed <MM/DD/YYYY>. [PMID: 26389305]
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Last Revised: 2020-01-03
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