Alcohol raises risk of cancer by damaging the DNA

Alcohol can increase the risk of developing cancer by causing permanent genetic damage to stem cells in the body, new research has found.

The study, conducted on genetically modified mice, adds to the growing evidence of a strong link between drinking and cancer.

Previous studies, including a meta-analysis published in 2016 combining years of scientific research, have linked alcohol to seven types of cancers, including the mouth and throat, larynx, oesophagus, liver, colon, bowel and breast.

Professor Linda Bauld, of Cancer Research UK – which part-funded the latest study by the MRC Laboratory of Molecular Biology in Cambridge – said: “We know that alcohol contributes to over 12,000 cancer cases in the UK each year, so it’s a good idea to think about cutting down on the amount you drink.”

Scientists at the MRC lab identified a chemical compound called acetaldehyde – which is produced as the body digests alcohol – as the cause of genetic damage.

Their findings back previous research from the University of Minnesota in 2012 linking acetaldehyde to irreversibly altering DNA in the cells.

The body already has a defence mechanism to protect against the harmful effects of alcohol – a group of enzymes called acetaldehyde dehydrogenases (ALDH) produced in the liver, which can neutralise acetaldehyde.

But when alcohol is consumed faster than the body’s ability to process it, acetaldehyde can build up in the cells.

Prof. Ketan Patel, from the MRC lab, said: “Some cancers develop due to DNA damage in stem cells.

“While some damage occurs by chance, our findings suggest that drinking alcohol can increase the risk of this damage.”

In order to see how acetaldehyde affects cells, the team genetically modified mice with a mutation that prevented blood stem cells from producing one of the ALDH enzymes, called ALDH2.

After giving the mice diluted alcohol, the team used chromosome analysis and DNA sequencing to look for genetic damage.

They found that the rodents deficient in ALDH2 had four times the DNA damage in their cells compared with the control mice with normal levels of the enzyme.

According to Prof. Patel, cells also have a second line of defence – a range of DNA repair systems which can fix and reverse different types of DNA damage. But in some people – particularly people from South East Asia – the repair systems fail to work.

Prof. Patel said: “Our study highlights that not being able to process alcohol effectively can lead to an even higher risk of alcohol-related DNA damage and therefore, certain cancers.

“But it’s important to remember that alcohol clearance and DNA repair systems are not perfect and alcohol can still cause cancer in different  ways, even in people whose defence mechanisms are intact.”