Cancer | Causes & Risk Factors


Who is at risk for cancer?

Everyone has some risk for cancer. In the United States, cancer is likely to affect 1 in 2 men and 1 in 3 women at least once in their lifetime. The amount of risk you have depends on a number of factors. These factors include tobacco use, lifestyle choices (such as diet and exercise), family history and factors in your workplace and environment.

How do I know if I am at risk for cancer?

Talk to your doctor. Your doctor can help you understand your risk for cancer, especially if other members of your family have a history of cancer. Your doctor can also help you understand how your risk for cancer is affected by the following:

  • Using or having used tobacco products, such as cigarettes or chewing tobacco
  • Drinking alcohol
  • Having eaten a diet high in fat for much of your life
  • Being exposed to chemicals that can cause cancer
  • Being at risk for skin cancer

Depending on your age and your risk factors, your doctor may begin screening you for certain types of cancer. Screening means looking for certain cancers before they cause any symptoms. Some doctors recommend that people who are at high risk or have a family history of cancer be screened more often, or at a younger age, than people who have average cancer risks. The recommendations for screening vary for different cancers.

How does smoking and other tobacco use affect my risk for cancer?

If you smoke, quitting smoking is the single most important thing you can do for your health. Cigarette smoking is a major cause of cancers of the lung, larynx (voice box), mouth and esophagus, and it can also contribute to cancers in other parts of the body.

According to the American Cancer Society, people who quit smoking at any age live longer than those who continue to smoke. For example, smokers who quit before age 50 have half the risk of dying within 15 years compared with those who continue smoking. And the more you smoke, the more damage you do. People who smoke 2 packs or more per day are nearly 20 times more likely to develop cancer than nonsmokers.

Other forms of tobacco can also cause cancer, such as cigars, chewing tobacco and snuff. If you use tobacco products and want to stop, talk to your family doctor. He or she can help you make a plan to quit.

How does my family history affect my risk for cancer?

Unfortunately, some types of cancer seem to run in families. People of a certain race or ethnic group may also have a higher risk of some kinds of cancer.

Your doctor will ask you whether other people in your family have had cancer. If someone in your immediate family (a parent, brother, sister or child) has had cancer, you probably are at higher risk for cancer, also.

You can't change your family history, but it helps to be aware of it. If you and your doctor know that cancer tends to run in your family, you can watch more closely for the early signs of the disease. For example, if you are a woman and have a family history of breast cancer, your doctor may want you to start having mammograms more often or at a younger age.

What about factors in my workplace or environment?

There may be substances in your surroundings that can cause cancer or put you at a higher risk of developing cancer. These can include dust and vapors in the air you breathe and chemicals that touch your skin. Exposure to the sun without protection can cause skin cancer and breathing tobacco smoke (by smoking yourself or by breathing secondhand smoke) puts you at risk of lung cancer and other types of cancers.

Ask your employer if there are any materials in your workplace that can cause cancer. These may include asbestos, solvents and chemicals used for manufacturing or cleaning, smoke or fumes from burning materials and many others. Your employer should have a material safety data sheet (MSDS) for each substance that could potentially damage your health. All employers are required by law to complete these forms and you have a right to see them. Your employer should also provide safety equipment, such as a mask and protective clothing, to help decrease your exposure to any harmful materials.

Take a look at the environments you spend time in outside your workplace, as well. Too much exposure to the sun can cause skin cancer, the most common form of cancer. Try to stay out of the sun as much as you can. If you must spend time in the sun, wear protective clothing and sunscreen with an SPF (sun protection factor) of at least 15.

Breathing in smoke from a cigarette, cigar or pipe (even if you're not the person who's smoking) causes damage to your body that can lead to cancer. If you smoke, you need to quit. If someone in your family smokes, offer to help him or her quit, or ask him or her to not smoke when you are around. Cigarette smoke that clings to surfaces like carpet or clothing can also pose a risk, especially for infants and toddlers.

Written by editorial staff

Reviewed/Updated: 02/14
Created: 06/02