We don’t know what causes all mouth or oropharyngeal cancers. But there are some factors that can increase your risk of developing it.
Having any of these risk factors does not mean that you will definitely develop cancer.
Smoking tobacco (cigarettes, pipes, cigars) increases your risk of developing mouth and oropharyngeal cancer. Research suggests that more than 60 out of 100 (more than 60%) of mouth and oropharyngeal cancers in the UK are caused by smoking.
There is some evidence that people exposed to second hand smoke (passive smoking) at home or in the workplace may have a small increase in their risk of mouth and oropharyngeal cancer.
Drinking alcohol increases your risk of mouth and oropharyngeal cancer. Research shows around 30 out of 100 (30%) of mouth and oropharyngeal cancers are caused by drinking alcohol.
Smoking and drinking together further increases the risk of cancer more than either by itself.
UK guidelines recommend a maximum of 14 units of alcohol a week for both men and women.
Chewing tobacco or betel quid
Smokeless tobacco, including chewing tobacco, such as betel quid (gutkha) or paan is known to cause mouth and oropharyngeal cancer. It is not a safe alternative to cigarettes. In the UK, it is often popular with South Asian communities.
A diet low in fruit and vegetables may increase your risk of mouth and oropharyngeal cancer. This might be due to a lack of vitamins and minerals. A balanced diet usually means you are getting enough vitamins and minerals.
Human papilloma virus (HPV)
The human papilloma virus (HPV) is a type of virus that infects the skin and the cells lining body cavities. For most people, HPV causes no harm and gets better on its own. You don't catch cancers like an infection. But the virus can cause changes in the mouth and throat making them more likely to become cancerous in the future.
HPV spreads through close skin to skin contact, usually during sexual activity. The virus is very common. But only a very small percentage of people with HPV develop mouth or oropharyngeal cancer.
The risk of HPV in the mouth and throat is linked to certain sexual behaviours, such as oral sex, and having a higher number of sexual partners.
Weak immune system
Your body's immune system fights infection. Some illnesses and medication can weaken your immune system. Research shows an increased risk of mouth cancer if you are:
- having treatment for HIV or AIDS
- taking medicines to suppress your immune system after an organ transplant
Sunlight and sunbeds
Too much ultraviolet (UV) radiation from the sun or sunbeds is the main cause of skin cancer. Skin cancers are relatively common on the head and neck as these areas are often exposed to UV radiation. Skin cancer can develop on the lip.
People who have had a mouth or oropharyngeal cancer have an increased risk of getting a second one.
People who have the following cancers are also at increased risk of mouth and oropharyngeal cancer:
- cancer of the food pipe (oesophagus)
- squamous cell skin cancer
- cervical cancer
- penile cancer
- anal cancer
Research shows a slight increase in risk of mouth and oropharyngeal cancer if you have a close relative (parent, sibling, or child) who has had mouth cancer. Further research is needed to understand why this is.
Changes can happen in the cells in the lining of the mouth. They can appear as red or white patches. The red patches are called erythroplakia. White patches are called leukoplakia.
In some people, these conditions may develop into cancer over some years. Doctors call these conditions pre cancerous.
Dentists can spot these patches during your dental appointments, so it is important to go for regular check ups.
People with certain conditions caused by inherited cell changes (mutations) have an increased risk of mouth and oropharyngeal cancer. These conditions include:
- Fanconi anaemia (a genetic condition affecting the bone marrow)
- dyskeratosis congenita (a condition causing changes to bone marrow, skin or fingernails)
Blood pressure drug (hydrochlorothiazide)
Hydrochlorothiazide is a drug to treat high blood pressure (hypertension). A side effect is increased sensitivity to sunlight (photo sensitivity). A small study showed this medicine might lead to an increased risk of developing lip cancer.
Stories about potential causes of cancer are often in the media and it isn’t always clear which ideas are supported by evidence. There might be things you have heard of that we haven’t included here. This is because either there is no evidence about them or it is less clear.
An example of this is teeth whiteners. Teeth whiteners have become widely used in recent years. Dentists can apply them, but some types are available for people to use at home.
There is no proof that teeth whiteners cause mouth cancer. But there has been very little research into a possible connection between the two. So you should always check first with your dentist before using these products.