Cancer of the mouth and throat: Overview
Tumours in the mouth and throat include both benign and malignant types.
- Benign tumours, although they may grow and penetrate below the surface layer of tissue, do not spread by metastasis to other parts of the body.
- Benign tumours of the oropharynx are not discussed here.
Pre-malignant conditions are cell changes that are not cancer but which may become cancer if not treated.
- Dysplasia is another name for these pre- cancerous cell changes.
- Dysplasia can be detected only by taking a biopsy of the lesion - this means to collect a tiny sample of the abnormal area.
- Examining the dysplastic cells under a microscope indicates how severe the changes are and how likely the lesion is to become cancerous.
- The dysplastic changes are usually described as mild, moderately severe, or severe.
The two most common kinds of pre-malignant lesions in the oropharynx are leukoplakia and erythroplakia.
- Leukoplakia is a white or whitish area. It can often be easily scraped off without bleeding. Only about 5% of leukoplakias are cancerous at diagnosis or will become cancerous within 10 years if not treated.
- Erythroplakia is a raised, red area. If scraped, it may bleed. Erythroplakia is generally more severe than leukoplakia and has a higher chance of becoming cancerous over time.
- These are often detected by a dentist at a routine dental examination.
Several types of malignant cancers occur in the mouth and throat.
- Squamous cell carcinoma is by far the most common type, accounting for more than 90% of all cancers. These cancers start in the squamous cells, which form the surface of much of the lining of the mouth and pharynx. They can invade deeper layers below the squamous layer.
- Other less common cancers of the mouth and throat include minor salivary gland tumours and lymphoma.
- Cancers of the mouth and throat do not always metastasise, but those that do usually spread first to the lymph nodes of the neck. From there, they may spread to more distant parts of the body.
- There are more than 6,700 new cases of oral cancers diagnosed in the UK each year.
- More than 2,000 deaths occur each year from oral cancers in the UK
- The incidence of oral cancers has been gradually increasing in the UK over the past 25 years.
- Cancers of the mouth and throat occur in around twice as many men as women.
These cancers can develop at any age but occur most frequently in people aged 45 years and older.
Incidence rates of mouth and throat cancers vary widely from country to country. These variations are due to differences in risk factor exposures.
Mouth and throat cancer causes
Tobacco use is by far the most common risk factor for cancers of the mouth and throat. Both smoking and ‘smokeless’ tobacco (snuff and chewing tobacco) increase the risk of developing cancer in the mouth or throat.
- Smokers are between three to five times more likely to have cancer of the mouth and throat than people who don't smoke. All forms of smoking are linked to these cancers, including cigarettes, cigars and pipes. Tobacco smoke can cause cancer anywhere in the mouth and throat as well as in the lungs, the bladder, and many other organs in the body. Pipe smoking is particularly linked with lesions of the lips, where the pipe comes in contact with the tissue.
- Smokeless tobacco is linked with cancers of the cheeks, gums and inner surface of the lips. The risk of these cancers is much greater in people who use smokeless tobacco than in those who do not. Cancers caused by smokeless tobacco use often begin as leukoplakia or erythroplakia.
Other risk factors for mouth and throat cancer include the following:
- Alcohol use: At least three-quarters of people who have a mouth and throat cancer consume alcohol frequently. People who drink alcohol frequently are five times more likely to develop one of these cancers. People who both drink alcohol and smoke often have a much higher risk than people who use only tobacco alone - according to the NHS smoking more than 40 cigarettes a day and drinking an average of 30 units of alcohol a week makes someone 38 times more likely to develop mouth or throat cancer.
- Ultraviolet light exposure: People who spend a lot of time in sunlight, such as those who work outdoors, are more likely to develop cancer of the lip.
- Chewing betel nut, a prevalent practice in India and other parts of South Asia, has been found to result in mucosa carcinoma of the cheeks.
- Human papillomavirus ( HPV) infection: Several strains of HPV are associated with cancers of the cervix, vagina, vulva and penis. The link between HPV and oral cancers is not known, but HPV infection is believed to increase the risk of oral cancers in some people.