Smoking and Cancer

Author: Allyson Van Horn, MPH
Last Reviewed: February 17, 2026

Most people know smoking and tobacco use can cause lung cancer, but they can also cause other illnesses:

Smoking also affects the health of those around you through secondhand smoke exposure. Children are more sensitive to the health effects of secondhand smoke.

How does tobacco cause cancer?

Tobacco and tobacco smoke cause cancer because they are made up of many chemicals called carcinogens (cancer-causing agents). Cigarettes, cigars, chewing, and pipe tobacco are made from dried tobacco leaves. They often have ingredients added for flavor to make smoking more pleasant. More than 7,000 chemicals have been found in tobacco and tobacco smoke. More than 60 of these are known to cause cancer.

Some of the chemicals in tobacco smoke are ammonia, arsenic, benzene (also found in pesticides and gasoline), cyanide, formaldehyde, tar, and carbon monoxide. Chemicals are also found in smokeless tobacco, like Polonium 210 (nuclear waste), cadmium (used in car batteries), lead (which causes nerve poison), nitrosamines, arsenic, and cyanide.

The chemicals in tobacco and tobacco smoke cause damage to the cells and genes in our bodies. The genetic damage caused by smoking leads to uncontrolled cell growth. This uncontrolled growth can lead to tumors. These tumors can grow and spread throughout your body.

What is my risk of getting lung cancer?

Your risk of getting lung cancer is a lot higher if you smoke compared to people who do not smoke. About 85 out of 100 lung cancer deaths are linked to smoking cigarettes. The risk is also high for all types of tobacco products.

Researchers at Memorial Sloan Kettering Cancer Center made an online tool that can be used to look at lung cancer risk for current or former smokers. It is used for people between 50 and 80 years old who have smoked for at least 20 years, or if they have quit within the past 15 years. This tool only looks at lung cancer risk and not the risk of the other cancers or health issues.

You can talk with your provider about your risk. Your risk is based on the amount you smoked, over what time span, and other parts of your health history that can increase your risk (asbestos exposure, COPD).

Is there a benefit to quitting smoking?

Yes! No matter how long or how much you have smoked, quitting lowers your risk of cancer and other smoking-related health problems. Quitting is not easy. Talk with your provider for help quitting. Use the links below to learn more about smoking’s health effects and quitting.

You should always be honest with providers about your smoking history and be aware of your risks.

Call your provider if you have any of these symptoms:

  • A change in a cough (for example, you cough up more phlegm or mucus than usual).
  • A new cough.
  • Coughing up blood.
  • Hoarseness (scratchy or weak voice).
  • Trouble breathing.
  • Wheezing.
  • Chest pain.
  • Loss of appetite.
  • Weight loss.
  • Feeling tired all the time (fatigue).
  • Frequent lung or respiratory infections (like pneumonia or bronchitis).
  • Sores or white patches in your mouth.

Smoking increases your risk of cancer and other health issues. If you want help quitting, talk to your provider about resources.

Resources for More Information:

The Benefits of Quitting Smoking

Secondhand Smoke and Health Risks

Quit Smoking: The Basics

Smoking Cessation: Where do I start?

Smoking Cessation Aids