Previous research looking at the precise ways in which alcohol causes cancer has been done in cell cultures.
But in this study, funded by Cancer Research UK, Wellcome and the Medical Research Council, researchers used mice to show how alcohol exposure leads to permanent genetic damage.
Scientists at the MRC Laboratory of Molecular Biology in Cambridge gave diluted alcohol, chemically known as ethanol, to mice.
They then used chromosome analysis and DNA sequencing to examine the genetic damage caused by acetaldehyde – a harmful chemical produced as the body processes alcohol.
It was found that acetaldehyde can break and damage DNA in blood stem cells, leading to rearranged chromosomes and permanently altering the DNA sequences in the cells.
Experts said the findings shed new light on how drinking alcohol increases the risk of developing certain cancers, including some of the most common types such as breast and bowel.
Professor Linda Bauld, cancer prevention expert at Cancer Research UK, said: “This thought-provoking research highlights the damage alcohol can do to our cells, costing some people more than just a hangover.
“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.”
Alcohol is known to cause seven types of cancer: mouth, upper throat, laryngeal, oesophageal, breast, liver and bowel. It is not thought to cause blood cancers but studying these stem cells offer a valuable way for researchers to examine what’s happening to the DNA inside.
Lead researcher Professor Ketan Patel, a scientist at the MRC Laboratory of Molecular Biology, 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.”
The study also examined how the body tries to protect itself against damage caused by alcohol.
The first line of defence is a family of enzymes called aldehyde dehydrogenases (ALDH). Millions of people worldwide either lack or carry faulty versions of these enzymes.
The study found mice without the enzyme suffered four times as much DNA damage as those with fully functioning ALDH when given alcohol.