Alcohol Containing Mouthwashes and Oral Cancer.

Over the last few years concern has been raised as to the association between long term use of alcohol containing mouthwashes and the development of oral cancer. The early research used the common one size fits all approach but clearly this is not appropriate now we know some of the underlying genetics of the susceptibility to oral cancers.

Upper airway, oesophageal and oral cancers have been found to occur with increased frequency in East Asian populations and we are now starting to understand why this occurs. It appears that a major susceptibility risk is associated with an increased conversion of alcohol to acetaldehyde and its subsequent conversion to acetate. This conversion is dependent principally on two enzymes, Alcohol dehydrogenase (ALD) and Aldehyde dehydrogenase (ALDH). The intermediary metabolite acetaldehyde is a highly toxic substance and has mutagenic properties (can induce mutations that increase the risk of development of cancer).

In the East Asian populations the alcohol dehydrogenase (ALD) is ~11 fold faster than that seen in Western Europeans so they convert alcohol to acetaldehyde at a higher rate than in Europeans. However up to 45% of the East Asian population carry a mutation of the Aldehyde Dehydrogenase (ALDH2), which is non-functioning. Whilst ~45% may carry the gene at least 10-20% may be homozygote and carry two non-functioning genes. These homozygote individuals have to use other genetic mechanisms of removal of alcohol and acetaldehyde. Exposure of these individuals to alcohol usually results in facial flushing (they get a red face rapidly after drinking alcohol and get very bad hangovers). These people are the ones at high risk of development of oral cancers.

A chronically heavy drinking European has a risk rate of development of an oral carcinoma of ~2 fold that seen with non-drinkers of the same genetic population. The heterozygote ALDH2 East Asians have risk rates of ~20-30 fold whilst the homozygote ALDH2 East Asians have risk rates in the order of 300+ fold of their non-drinking non-carrier individuals from the same population.

Some common mouthwashes have alcohol concentrations in the order of 20-26%. Since the risk was made apparent by Professor Michael McCullough the companies have released alcohol free mouthwashes. It is recommended that those members of the population with East Asian descent, who are facial flushers when drinking alcohol, should only use the alcohol free versions of the mouthwashes, if they use them chronically. It is highly unlikely that intermittent use of these products will increase the risk of development of oral carcinoma in these individuals.

Below is a copy of a lecture presenting the data at a high scientific level for those that are interested?

© Penam Investments Pty Ltd 2014.

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