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Risk factors for oral cancer
A risk factor is something that increases the risk of developing cancer. It could be a behaviour, substance or condition. Most cancers are the result of many risk factors. Tobacco and alcohol are the most important risk factors for oral cancer.
Oral cancer is rare in children and young adults. The risk of developing oral cancer increases with age and is greatest after 45 years of age. More men than women develop oral cancer, and it occurs more often in men of African descent.
Precancerous conditions of the mouth include leukoplakia and erythroplakia. They aren’t cancer, but they can sometimes become oral cancer if they aren’t treated. Some of the risk factors for oral cancer may also cause these precancerous conditions. Find out more about precancerous conditions of the mouth.
Risk factors are generally listed in order from most to least important. But in most cases, it is impossible to rank them with absolute certainty.
|Known risk factors||Possible risk factors|
Known risk factors
There is convincing evidence that the following factors increase your risk for oral cancer.
Most oral cancers are linked to tobacco use. All forms of tobacco increase the risk for this cancer, including cigarettes, cigars, pipes, bidis and smokeless tobacco (including chewing tobacco and snuff). The longer you use tobacco and the more you use, the greater your risk. The risk for oral cancer greatly increases when smoking is combined with using smokeless tobacco, drinking alcohol or both. Continuing to smoke after treatment for oral cancer increases the risk of developing a second oral cancer.
Smoking cigarettes, cigars or pipes increases the risk for oral cancer. These products are often linked with cancer of the lip if they sit on the lips. Using smokeless tobacco products is linked with cancer of the gums and inner lining of the cheeks and lips because the tobacco regularly touches these areas.
Some studies show that second-hand smoke may also increase the risk for oral cancer.
Alcohol is one of the main risk factors for oral cancer. The more you drink, the greater your risk. Using alcohol and tobacco together increases the risk of developing oral cancer more than using either one alone.
Chewing betel quid or areca nut is common in South Asia and among some South-Asian immigrants in Canada. Betel quid, or paan, is areca nut (the seed from the fruit of the oriental palm) and lime wrapped in a betel leaf. Some people chew areca nut by itself. Betel quid and tobacco are often chewed together, or betel quid may contain tobacco.
Betel quid and areca nut contain cancer-causing substances. People who chew betel quid or areca nut have a higher risk of developing oral cancer, especially in the inner lining of the cheeks and lips.
HPV is a group of more than 100 different types of related viruses. Many types of HPV are spread through sexual contact, including oral sex. They can infect the sexual organs (the penis in men or the vulva, vagina and cervix in women), the rectum and the anus. They can also infect the mouth and throat.
The different types of HPV are usually given a number to identify them. Infection with HPV-16 increases the risk of oral cancer. Infection with HPV-18 may also increase the risk. HPV is likely the cause of oral cancer that is not linked with tobacco or alcohol use.
People who have had oral cancer have a higher risk of developing another oral cancer, especially if they continue to use tobacco or alcohol. Having cancer of the esophagus, larynx, lung or cervix also increases your risk of oral cancer.
SCC is the most common type of oral cancer. There is a higher risk of developing SCC in the head and neck region (including the mouth) if a first-degree family member (parent, sibling or child) has been diagnosed with SCC of the head and neck.
Sun exposure increases the risk of developing lip cancer. This is especially true for people who work in the sun for long periods of time, such as farmers. Fair-skinned people also have a greater risk of developing lip cancer. Most lip cancers occur on the bottom lip, likely because it’s more exposed to the sun.
Many studies show that not eating enough vegetables and fruit increases the risk of developing oral cancer. Substances like carotenoids, which are common in vegetables and fruit, are linked with a lower risk of oral cancer.
Your immune system can be weakened after an organ transplant or treatment for an immune system disease. People with a weakened immune system have a higher risk of developing oral cancer, especially lip cancer. The higher risk may be due to taking drugs that suppress your immune system. People with weakened immune systems are also more likely to get an HPV infection, which increases the risk for oral cancer.
People who have a stem cell transplant may develop GVHD. GVHD is when the healthy transplanted stem cells see the body as foreign and start to destroy the body’s cells, including cells in the mouth. Damage to cells in the mouth from GVHD increases the risk of developing oral cancer.
Find out more about graft-versus-host-disease (GVHD).
Lichen planus is a chronic condition that forms a rash or sores on the skin and inside the mouth, usually on the tongue, gums and lining of the cheeks. Sometimes the sores can develop into ulcers. Having lichen planus with ulcers in the mouth for a long time increases the risk of developing oral cancer.
People with poor oral health may have several missing teeth, bleeding gums or chronic infections from bacteria and viruses like HPV. They may not go to the dentist very often to take care of their mouth. Studies show that people with poor oral health have a higher risk of developing oral cancer.
An inherited, or genetic, condition is passed from parents to their children through genes. People with the following inherited conditions have a higher risk of developing precancerous changes in the mouth and oral cancer. These develop at a much earlier age than oral cancer caused by other risk factors.
Fanconi anemia is a rare genetic condition that affects the bone marrow so it can’t make enough red blood cells, white blood cells or platelets.
Dyskeratosis congenital is a genetic syndrome that can cause abnormal red blood cells, skin rashes and abnormal fingernails and toenails.
Possible risk factors
The following factors have been linked with oral cancer, but there is not enough evidence to show they are known risk factors. More research is needed to clarify the role of these factors for oral cancer.
A few studies found that having dentures that don’t fit properly can increase the risk for oral cancer. This may because the dentures rub on the gums and cause sores that may develop into a cancerous tumour.
Some studies found that people who drink very hot beverages may have a higher risk for oral cancer. The hot beverage may cause damage to the cells in the mouth, which may develop into a cancer.
Unknown risk factors
It isn’t known whether or not the following factors are linked with oral cancer. It may be that researchers can’t show a definite link or that studies have had different results. More research is needed to see if the following are risk factors for oral cancer:
- using alcohol-based mouthwash
- smoking cannabis (marijuana)
- infection with human immunodeficiency virus (HIV) or having acquired immunodeficiency syndrome (AIDS)
Questions to ask your healthcare team
To make the decisions that are right for you, ask your healthcare team questions about risks.
I’m extremely grateful to the Canadian Cancer Society for funding my research with an Innovation Grant.
What’s the lifetime risk of getting cancer?
The latest Canadian Cancer Statistics report shows about half of Canadians are expected to be diagnosed with cancer in their lifetime.