Introduction

Oral cancer, also known as mouth cancer, is a type of head and neck cancer that can affect any part of your mouth - including the lips, tongue, gums, cheeks, and the roof or floor of the mouth. There are several types of oral cancer, each type differs according to the cells that the cancer starts in.

The most common type of oral cancer is squamous cell carcinoma (SCC), which accounts for over 90% of oral cancers and originates in the flat, skin-like cells that cover the inside of the mouth.¹ If left untreated, oral cancer can lead to difficulties with speaking, chewing, swallowing, and even breathing; on top of this, it can spread to other parts of the body and become life-threatening. 

Like all cancers, oral cancer is caused by the uncontrolled growth of mutated cells. The mutations that can lead to oral cancer are associated with certain risk factors that relate to things like your lifestyle and family history. It is, therefore, essential to be aware of the risk factors for oral cancer so that you can take proactive steps to minimise your chances of developing the disease. 

Risk factors

Tobacco use

Tobacco use is a major risk factor for many types of cancer, one of which is oral cancer. All tobacco products contain toxins and carcinogens (cancer-causing agents), which explains why people who consume these products are at a higher risk of developing cancer.¹¹

The most common method of tobacco consumption is smoking cigarettes. Data shows that cigarette smokers are 7 to 10 times more likely to develop oral cancer than non-smokers, with more than 60 toxic chemicals known to be present in tobacco.¹ 

Smoking cigars and pipes also significantly increases the risk of developing oral cancer. With cigars, this risk is associated with the increased burning time and tobacco content compared to cigarettes.¹¹ With pipes, there is an especially high risk of developing lip cancers due to the prolonged resting of the pipestem on the lip. 

Smokeless tobacco - namely chewing tobacco and snuff - also increases your oral cancer risk, with more than 28 cancer-causing chemicals identified in this form of tobacco.¹² If you consume smokeless tobacco products, you are particularly at risk of developing cancer in the areas where the tobacco is held - that is, the cheek, gums, and lips. These cancers often begin as white or red patches in the mouth, known as leukoplakia and erythroplakia.²

Alcohol consumption

Regular consumption of alcohol is another major risk factor for oral cancer, with approximately 35% of mouth and oropharyngeal cancer diagnoses in the UK attributed to alcohol.¹³ For moderate drinkers, the risk of developing oral cancer (excluding lip cancer) is almost twice as high as for non-drinkers, while the risk for heavy drinkers is over five times higher than for non-drinkers.³

Furthermore, your oral cancer risk is substantially higher if you regularly consume alcohol and also use tobacco.⁴

To minimise your risk of developing oral cancer and to maintain overall health, it is advised that you follow the UK drinking guidelines. These guidelines recommend that you consume no more than 14 units of alcohol per week.

Diet

Your dietary choices can also influence your oral cancer risk. In particular, research suggests that consuming sufficient amounts of fruit and vegetables can reduce your risk while consuming high quantities of red meat and fried foods can increase your risk. Alongside fruit and vegetables, curcumin - the active ingredient in turmeric - and green tea can also reduce your risk of developing oral cancer due to their anti-inflammatory properties.⁵

Ensure you follow a balanced diet rich in fruit and vegetables to maximise your health and reduce your risk of developing oral cancer. 

Human papillomavirus (HPV) infection

If you have been infected with human papillomavirus (HPV), you may be at an increased risk of developing oral cancer. While HPV infection is common, affecting around 80% of people in their lifetime, certain strains are classified as ‘high-risk’ and can increase your risk of cancer. Different high-risk strains are linked with different types of cancer - with oral cancer most commonly associated with HPV 16.¹³ 

Most of the time, your immune system will clear up an HPV infection on its own and you won’t realise you ever had it. However, high-risk types - such as HPV 16 - can persist for a long time and change the DNA inside your cells. These DNA changes can cause the affected cells to divide and grow out of control - eventually causing cancer. 

HPV is a sexually transmitted infection (STI), so you can reduce your risk of infection by practising safe sex. This involves using condoms or dental dams during sex - including oral sex. It is important to note that these will not provide complete protection as they don’t cover the whole genital area; however, they can help reduce the risk. 

Other steps that you can take to reduce your risk are as follows:

• Get vaccinated against high-risk HPV types.¹⁴ All children aged 11-13 in the UK are offered this vaccine; you can also get it for free up to the age of 25 if you missed it when offered. Additionally, it is available for men who have sex with men and some transgender people up to the age of 45. If you are not in any of these groups and have not had the vaccine, speak to your doctor as it can be offered on a case-by-case basis. Alternatively, you can pay to have the vaccine privately 
• Stop smoking as this can weaken your immune system, making it harder to protect against HPV and clear infections. Smoking is also a distinct risk factor for oral cancer

Weak immune system

Having a weakened or suppressed immune system means your body is less able to fight infection and kill abnormal cells that can lead to cancer.¹⁵ This results in a higher risk of developing cancer, including oral cancers; studies suggest that immunosuppression increases your oral cancer risk by 0.2% to 1%.⁶

You will have a weak immune system if you:

• Have HIV/AIDS
• Take medication to suppress your immune system - for example, after an organ transplant or to treat an autoimmune disease

Additionally, if you have a weak immune system, you are at a higher risk of persistent HPV infection - which, as discussed, is another risk factor for oral cancer.¹⁶ 

Family history

Some studies have suggested an increased risk of oral cancer if you have a very close relative, such as a sibling or parent, who has or has previously had head and neck cancer.^7,8 Further research is needed to identify the reasons behind this. 

Previous cancer

If you have previously had certain types of cancer, you are at an increased risk of developing oral cancer. Previous cancers that increase your risk are:

• Head and neck cancers, including previous oral cancer
• Squamous cell cervical cancer
• Oesophageal squamous cell cancer 
• Lung cancer

Sun exposure

High exposure to ultraviolet (UV) radiation from the sun or sunbeds is associated with an increased risk of lip cancer. This risk is higher if you do not use lip protection - such as lip balms with high SPF.⁹

Physical activity

Being active is beneficial for your overall health and can also reduce your risk of multiple different cancers. One of these is oral cancer, with research suggesting a moderately lower risk of oral cancer in physically active individuals.¹⁰

Summary

Multiple factors increase the risk of developing oral cancer, with the most influential being tobacco use and alcohol consumption. You can reduce your risk by avoiding tobacco products and consuming no more than 14 units of alcohol per week. Additionally, following a healthy diet and being mindful of other risk factors like HPV and your family history can minimise your risk and increase your awareness. It is also essential to have regular dental check-ups to maintain your oral health and identify any changes that could indicate cancer.