A risk factor is anything that increases your chance of getting a disease. Oral cancer has many risk factors, some of which pose a bigger threat than others.
Doctors do not know exactly what causes one person to develop oral cancer and another not to- there are just too many variables to consider. Improving our knowledge of these risk factors will however, help to prevent the disease
Oral cancer itself is not contagious and you cannot catch it from another person, but you could catch HPV the leading cause.
- HPV. The association of HPV with cervical cancer is well established and now its link to oral cancer is gaining weight with the predominant mode of transmission - oral sex. There are many different strains of HPV (120 we know about) and the majority of which, do not cause cancer. The cervical cancer causing HPV 16 and 18 are of particular concern.
1 in 2 sexually active people is at risk of HPV infection and the only way to truly protect yourself is to wear a condom for all sexual activities.
- Alcohol. Alcohol consumption has long been regarded as a principal risk factor in oral cancer and like smoking- the more you do it, the greater the risk. It was the alcohol content in Listerine that caused the media to jump on Listerine as a possible cause of oral cancer. Pure ethanol is not considered carcinogenic and different alcoholic compounds will have different effects. There are always arguments for and against these things and evidence and statistics available for each. I can say that after reading everything everything about alcohol mouthwashes, I am happy for my patients to continue using a short 30 second rinse once a day, but since they introduced the new alcohol free version I have recommended changing to that where possible.
- Tobacco. Tobacco contains over 60 carcinogens (cancer forming substances/chemicals) that can irritate the tissues inside your mouth. Any form of tobacco smoking: cigarettes, cigars, pipes, reverse smoking or chewing tobacco carries a strong risk factor for oral cancer. The more you smoke the more you are at risk. Holding smoke in your mouth for extended periods and not taking it down into your lungs, may make you a little less likely to get lung cancer but you simply swap that risk for oral cancer- so do yourself and body a favour, stop thinking about quitting and actually do it.
- Smoking and drinking. Together, these have been shown to have an increased risk (by a factor of up to 4 times), compared to smoking and drinking at separate times. It is thought that the alcohol makes your mucosa more susceptible to the carcinogens in tobacco allowing them to diffuse through your tissues more easily and penetrate more deeply(7).
Heavy drinker/ non smoker = about 2.5 times the risk
Non drinker/ heavy smoker = about 10 times the risk
Heavy drinker/ heavy smoker= about 25 times the risk
- Location. Different habits, lifestyles and genetic dispositions mean oral cancer varies from country to country and continent to continent.
It is responsible for:
1-2% of all cancers in the UK and Australia
2-4% in the USA
30-40% in India- yes you read that correctly!
- Ultraviolet light. We all know the risks of sun exposure in developing skin cancer, particularly in Australia, where this affects 2 out of 3 Australians in their lifetime. Well, your lips are particularly vulnerable to UV light and oral cancer of the lower lip particularly, is very common in fisherman, labourers and individuals who spend the majority of their time working outdoors.
- Betel nut. Chewing betel, paan and areca is a major risk factor in developing oral cancer. The habit is a very common one, especially on the Indian Sub-continent and Southeast Asia where it is responsible for 40% of oral cancers. It is often combined with tobacco and chewed for very long periods and this habit can start in childhood. A white patch (leukaplakia) develops in the mouth which later turns into full blown oral cancer. If you look at the reported cases of oral cancer, India is the world leader and this betel/tobacco habit seems largely to blame and is reported to increase your risk by 8-15 times (8).
- Chronic trauma.Over time any chronic trauma has the potential to be a risk factor- this could be from an ill-fitting denture, sharp fillings or rough teeth.
- Pre-malignant lesions. These lesions can show some abnormal changes in your cells (dentists call this dysplagia) and over time (months or even years), they have the potential to lead to oral cancer and as such, must be treated or monitored closely. The amount of abnormal cells can be classified as moderate dysplagia or severe dysplasia. This reflects the degree of change and level of risk. Efforts should be taken to reduce risk factors; such as stopping smoking and limiting alcohol intake- hopefully things will improve. These lesions should be monitored every 6 months and re-biopsied at suitable intervals or treated by surgical or laser removal.
- White and red patches. These white and red patches of unknown cause are known, in dentist speak as 'leukoplakia' and 'erythroplakia' respectively. Bright red velvety patches are 17 times more likely to undergo malignant change than white patches. Less than 10% of leukaplakia will turn malignant and other risk factors such as smoking, drinking and nutritional deficiencies may play some role in how many do (9).
- Oral lichen planus. A chronic inflammatory condition that affects 1-2% of the UK population. If there is an association with oral cancer it is only with the atrophic or erosive types of the condition (10).
- Discoid lupus erythematosus (11)
- Chronic hyperplastic candidiasis
- Nutritional deficiencies. Numerous studies have demonstrated the protective role that proper nutrition can have in preventing cancer and so a particularly poor diet may place you at an increased risk.
- Immunosuppresion. Any conditions that affect our bodys ability to defend itself and fight infection makes us more susceptible to developing cancer. Oral cancer has been found to be more common in HIV cases and renal transplant patients.
- Previous head and neck cancer. Patients who have had one bout of oral cancer are at high risk for developing further lesions and therefore these patients need even more careful monitoring and thorough cancer screening every 6 months.
- Family history of cancer. Genetic factors are likely play some role in the susceptibility to oral cancer though this has not clearly been demonstrated.
Thank you to this interesting article by Dr Murray Walker about about oral cancers in New South Wales