Oral cancer causes and risk factors

This page was reviewed under our medical and editorial policy by

Maurie Markman, MD, President, Medicine & Science

This page was updated on September 12, 2022.

More than 58,000 new cases of oral cancer are diagnosed in the United States each year, according to the American Cancer Society, representing about 3 percent of all cancers diagnosed. In the United States, oral and oropharyngeal cancers are the eighth most common cancers among males.

Cancers of the mouth and the back of the throat are considered oral cancers. They may form:

  • On the tongue
  • Under the tongue
  • At the base of tongue
  • In the tissue lining the mouth and gums
  • In the throat
  • At the back of the mouth

Cancers of the mouth are divided into the two categories below.

Oral cavity cancer may develop in the:

  • Lips (known as lip cancer)
  • Inside the lips and cheeks, where it can develop into a form of mouth cancer called buccal mucosa cancer
  • Gums (known as gum cancer)
  • The front of the tongue (known as tongue cancer)
  • The floor and roof of the mouth (known as floor of mouth cancer or hard palate cancer)

Oropharynx cancer is a type of throat cancer that forms in the middle part of the throat, including the tonsils and tongue’s base.

What causes oral cancer?

While the exact cause of oral cancer isn't known, several factors are known to increase risk, including human papillomavirus (HPV) infection, tobacco use and alcohol consumption.

Oral cancer risk factors

Some factors may increase the likelihood of developing oral cancer. The risk of oral cancer increases with age; however, people younger than age 55 may develop the disease, as well. Men are also twice as likely as women to develop oral cancer.

Additional risk factors for developing oral cancer include those listed below.

Gender: Oral cancer is twice as common in men as in women. This difference may be related to the use of alcohol and tobacco, which are major oral cancer risk factors seen more commonly in men than in women.

HPV infection: HPV includes about 200 similar viruses. Many HPVs cause warts, but some lead to cancer. HPV is a risk factor for oral cancer. People with oral cancers linked to HPV tend to not be smokers or drinkers, and usually have a good prognosis. Typically, HPV infections in the mouth do not produce symptoms, and only a small percentage of these infections develop into cancer.

Age: The average age at diagnosis for oral cancer is 63, and more than two-thirds of individuals with this disease are over age 55, although it may occur in younger people, as well.

Ultraviolet light: Cancers of the lip are more common among people who work outdoors and visit tanning beds, and among those with prolonged exposure to sunlight.

Poor nutrition: Studies have found a link between diets low in fruits and vegetables and an increased oral cancer risk.

Genetic syndromes: Some inherited genetic mutations, which cause different syndromes in the body, carry a high risk of oral cancer. These include:

  • Fanconi anemia is a blood condition caused by inherited abnormalities in several genes. Patients may experience symptoms at an early age and may develop anemia or aplastic anemia. The risk of oral cancer among people with Fanconi anemia is up to 500 times higher than the general population.
  • Dyskeratosis congenita is a genetically linked syndrome that may also cause aplastic anemia, and carries a high risk of oral cancer, beginning at an early age.

Tobacco use: About 85 percent of patients with oral cancers use tobacco in the form of cigarettes, chewing tobacco or snuff. The risk of developing oral cancer depends on the duration and frequency of tobacco use. Smoking may lead to cancer in the mouth or throat, and oral tobacco products are associated with cancer in the cheeks, gums, and inner surface of the lips.

Alcohol: About 70 percent of people diagnosed with oral cancer are heavy drinkers. This risk is higher for people who use both alcohol and tobacco. For people who smoke and drink heavily, the risk of oral cancer may be 30 times higher than the risk for people who do not smoke or drink.

Betel quid: Many people in Southeast Asia and other parts of the world chew betel quid, a leaf from the betel plant wrapped around areca nut and lime. Chewing gutka, a combination of betel quid and tobacco, is also common. Both of these substances are associated with an increased oral cancer risk.

Immune system suppression: Taking drugs that suppress the immune system, such as those used to prevent rejection of a transplant organ or to treat certain immune diseases, may increase the risk of oral cancer.

Lichen planus: People with a severe case of this illness, which usually causes an itchy rash but sometimes appears as white lines or spots in the mouth and throat, may have a higher risk of oral cancer. Lichen planus usually affects middle-aged people.

Graft-versus-host disease (GVHD): This condition may develop after a stem-cell transplant, in which bone marrow is replaced following cancer occurrence or treatment. The new stem cells may cause an immune response that attacks the patient’s own cells, and tissues in the body may be destroyed as a result. GVHD increases the likelihood of oral cancer, which may develop as soon as two years later.

Next topic: What are the symptoms of oral cancer?

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