How diet, nutrition and physical activity affect mouth and throat cancer risk. In total, we analysed 25 studies from around the world, with more than 9 million participants and nearly 8,000 cases of mouth, pharynx and larynx cancers.
The mouth includes the lips, tongue, inside lining of the cheeks, floor of the mouth, gums, palate and salivary glands. Most of the studies identified for the evidence on this webpage did not include cancer of the lips or salivary glands.
The pharynx (or throat) is the muscular cavity leading from the nose and mouth to the larynx, a muscular structure at the upper area of the windpipe, which includes the vocal cords. Cancer of the nasopharynx (the area that connects the back of the nose to the back of the throat) is reviewed separately.
Our Expert Panel has reviewed the evidence on diet, weight, physical activity and the risk of mouth and oral cancers.
There is strong evidence that:
There is some evidence that:
In addition to the findings on diet, nutrition and physical activity outlined above, other established causes of mouth and oral cancers include:
Smoking (or the use of smokeless tobacco, sometimes called “chewing tobacco” or “snuff”) is a cause of mouth and oral cancers. Chewing betel quid (nuts wrapped in a betel leaf coated with calcium hydroxide), with or without added tobacco, is also a risk factor for cancers of the mouth and pharynx. It is estimated that as much as 90% of mouth cancers worldwide are attributable to tobacco use, alcohol consumption or a combination of both.
Oral infection with high-risk human papilloma viruses (HPV) is a risk factor for mouth cancer. It is estimated that 72% of oropharyngeal cancer is linked to high-risk HPV infection.
Exposure to asbestos increases the risk of laryngeal cancer.
Over 90% of oral cavity, pharyngeal and laryngeal cancers are squamous cell carcinomas.
Cancers of the mouth, pharynx and larynx, like other cancer types, are the result of genetic alterations that lead to small, localised lesions in the mucosal membranes (very thin membranes that cover the gastrointestinal tract from the mouth to the anus) that grow in an abnormal way (dysplasia). These lesions may then progress to carcinoma in situ and/or become invasive cancers.
Exposure to carcinogens can be prolonged and consistent. The mouth and pharynx are directly exposed both to inhaled carcinogens and through eating and drinking. Chronic damage and inflammation caused by stomach acid due to reflux are also implicated. Recent studies have reported that laryngopharyngeal reflux (where stomach acid flows upwards to the larynx and/or pharynx) is associated with laryngeal cancers.
Cancers of the mouth, pharynx and larynx frequently show multiple, independent, malignant foci (location of tumour cells can only be identified microscopically) – with second primary cancers occurring relatively frequently. This phenomenon (referred to as “field cancerisation”) occurs when an entire region of tissue is repeatedly exposed to carcinogens.
Full references and a summary of the mechanisms underpinning all the findings can be found in the mouth, pharynx and larynx cancers report.
In 2018, World Cancer Research Fund International published Diet, Nutrition, Physical Activity and Cancer: a Global Perspective on behalf of AICR, WCRF and WKOF. This was the third in our series of major reports looking at the many ways in which our diets, and how active we are, affect our cancer risk. You can find out much more about bladder cancer by downloading a pdf of the relevant chapter in the 2018 report. Please note, however, that this webpage may have been updated since the report was published.