When you get a diagnosis of cancer, it's natural to wonder what may have caused the disease. Doctors can't always explain why one person gets oral cancer and another doesn't.

However, we do know that people with certain risk factors may be more likely than others to develop oral cancer. A risk factor is something that may increase the chance of getting a disease.

Studies have found the following risk factors for oral cancer:

• Tobacco: Tobacco use causes most oral cancers. Smoking cigarettes, cigars, or pipes, or using smokeless tobacco (such as snuff and chewing tobacco) causes oral cancer. The use of other tobacco products (such as bidis and kreteks) may also increase the risk of oral cancer.
  
  Heavy smokers who have smoked tobacco for a long time are most at risk for oral cancer. The risk is even higher for tobacco users who are heavy drinkers of alcohol. In fact, three out of four people with oral cancer have used tobacco, alcohol, or both.

  How to Quit Tobacco Quitting is important for anyone who uses tobacco. Quitting at any time is beneficial to your health. For people who already have cancer, quitting may reduce the chance of getting another cancer, lung disease, or heart disease caused by tobacco. Quitting can also help cancer treatments work better. There are many ways to get help: Ask your doctor about medicine or nicotine replacement therapy. Your doctor can suggest a number of treatments that help people quit. Ask your doctor or dentist to help you find local programs or trained professionals who help people stop using tobacco. Call staff at the NCI Smoking Quitline at 1-877-44U-QUIT (1-877-448-7848) or instant message them through LiveHelp 1 (http://www.cancer.gov/help). They can tell you about: Ways to quit smoking Groups that help smokers who want to quit NCI publications about quitting smoking How to take part in a study of methods to help smokers quit Go online to Smokefree.gov 2 (http://www.smokefree.gov), a Federal Government Web site. It offers a guide to quitting smoking and a list of other resources.

• Heavy alcohol use: People who are heavy drinkers are more likely to develop oral cancer than people who don't drink alcohol. The risk increases with the amount of alcohol that a person drinks. The risk increases even more if the person both drinks alcohol and uses tobacco.
• HPV infection: Some members of the HPV family of viruses can infect the mouth and throat. These viruses are passed from person to person through sexual contact. Cancer at the base of the tongue, at the back of the throat, in the tonsils, or in the soft palate is linked with HPV infection. The NCI fact sheet Human Papillomaviruses and Cancer ³ has more information.
• Sun: Cancer of the lip can be caused by exposure to the sun. Using a lotion or lip balm that has a sunscreen can reduce the risk. Wearing a hat with a brim can also block the sun's harmful rays. The risk of cancer of the lip increases if the person also smokes.
• A personal history of oral cancer: People who have had oral cancer are at increased risk of developing another oral cancer. Smoking increases this risk.
• Diet: Some studies suggest that not eating enough fruits and vegetables may increase the chance of getting oral cancer.
• Betel nut use: Betel nut use is most common in Asia, where millions chew the product. It's a type of palm seed wrapped with a betel leaf and sometimes mixed with spices, sweeteners, and tobacco. Chewing betel nut causes oral cancer. The risk increases even more if the person also drinks alcohol and uses tobacco.

The more risk factors that a person has, the greater the chance that oral cancer will develop. However, most people with known risk factors for oral cancer don't develop the disease.

Glossary Terms

A cigarette made by rolling tobacco by hand in a dried leaf from the tendu tree (a member of the ebony family). Most bidis are made in India and they come in different flavors.

A type of virus that can cause abnormal tissue growth (for example, warts) and other changes to cells. Infection for a long time with certain types of HPV can cause cervical cancer. HPV can also play a role in some other types of cancer, such as anal, vaginal, vulvar, penile, and oropharyngeal cancers. Also called human papillomavirus.

A cigarette made of a mixture of tobacco and clove.

Something that increases the chance of developing a disease. Some examples of risk factors for cancer are age, a family history of certain cancers, use of tobacco products, being exposed to radiation or certain chemicals, infection with certain viruses or bacteria, and certain genetic changes.

A substance that helps protect the skin from the sun's harmful rays. Sunscreens reflect, absorb, and scatter both ultraviolet A and B radiation to provide protection against both types of radiation. Using lotions, creams, or gels that contain sunscreens can help protect the skin from premature aging and damage that may lead to skin cancer.

In medicine, a very simple microorganism that infects cells and may cause disease. Because viruses can multiply only inside infected cells, they are not considered to be alive.