Australian researchers say that there is now 'sufficient evidence' to prove the link. They propose that the ethanol allows carcinogens to permeate the lining of the mouth.
What is the research?
The findings are not based on any new research but on a review of a small number of existing studies.
The researchers examined the role of alcohol in the development of oral cancer, focusing on a study that found that the risk of developing oral cancer increased 50-fold in heavy drinkers compared with those who never drank. This study established the link between alcohol and cancer but did not look at the use of mouthwash.
Animal studies showed that high strength alcohol caused oral cancer by eliminating the lipid component of the barrier in the oral cavity. This makes the mouth more susceptible to chemical carcinogens such as acetaldehyde, a by-product of alcohol metabolism.
The link between mouth-wash use and cancer is based on four studies dating from 1983 to 2007. The review pla-ced greatest emphasis on the most recent study, which involved 3,210 patients with head and neck cancer and 2,752 controls.
Although the study found that mouthwash users were five times more likely to develop oral cancer than non-users, the study did not record the type of mouthwash used, the levels of alcohol content or for how long the participants had used mouthwash.
The review also notes that a number of studies failed to find any evidence to support a link between mouthwash use and cancer.
What do the researchers say?
Professor Michael McCullough of Melbourne Dental School wrote in the Dental Journal of Australia that it would be wise to restrict alcoholic mouthwashes to short-term use.
'There may well be a reason for the use of alcohol-containing mouthrinses, but only for a particular situation and for a limited and controlled period,' he said.
'It is the opinion of the authors that, in light of the evidence available of the association of alcohol-containing mouthwashes with the development of oral cancer, it would be inadvisable for healthcare professionals to recommend the long-term use of alcohol-containing mouthwashes,' he added.
What do other researchers say?
Yinka Ebo, health information officer at Cancer Research UK, said: 'We know that drinking too much alcohol is one of the causes of mouth cancer. So the idea that alcoholic mouthwashes could increase the risk of mouth cancer makes sense.
'But the evidence is inconsistent. It's important to note that mouthwash users may be more likely to have poor oral hygiene, so more research is needed to find out whether it's the mouthwash or poor oral hygiene that increases the risk of mouth cancer.'
- Using alcoholic mouthwash could increase the risk of oral cancer.
- Poor oral health, rather than mouthwash, may be to blame for the raised cancer risk.
- No studies have been conducted that specifically look at the long-term use of mouthwash or particular mouthwashes.