Alcohol damage to DNA is cause of cancer

New research has found how excessive alcohol consumption causes various types of cancer – by damaging the DNA of stem cells.

It has long been known that a build up of carcinogenic acetaldehyde – a chemical produced when the body processes alcohol – is the principal cause of seven types of cancer, especially breast cancer in women as well as bowel and mouth cancer.

What was not known exactly was how acetaldehyde caused the damage that led to these cancers developing.

On Wednesday this week (3 January), a team from the Medical Research Council Laboratory of Molecular Biology at Cambridge University published the findings of a study in the scientific journal Nature, which they say shows how unprocessed acetaldehyde can break the DNA of Haematopoietic stem cells (which renew red and white blood cells), permanently altering the genetic code and allowing cancerous cells to form.

The study also showed, however, how the body protects itself from acetaldehyde by using a group of enzymes called aldehyde dehydrogenases 2 (ALDH2), which break acetaldehyde down into acetate which cells can use beneficially.

DNA also has a range of repair systems that – for the most part – are able to fix damage although there is also the possibility that cells are improperly repaired which can also then turn cancerous.

An estimated 540 million people worldwide are thought to have a polymorphism in ALDH2 which means they are unable to successfully convert acetaldehyde into acetate – and are subsequently at greater risk of oesophageal cancer.

When mice lacking ALDH2 were given alcohol the researchers found that the damage to their subjects’ DNA was four times higher than those with properly functioning ALDH2.

The majority of people with these deficiencies are located in East Asia, particularly among Chinese.

Drink-related cancers in the UK are thought to account for 4% of total cases per year, affecting around 12,800 people.

The research can be found here (£).