DNA clue to how drinking raises your cancer risk

DRINKING alcohol damages DNA, increasing the risk of developing several types of cancer, researchers have discovered.

For the first time scientists have found a ‘simple plausible explanation’ for why alcohol can cause cells to go haywire and raise the risk of cancers including breast, mouth and throat, liver, colon and bowel.

When alcohol is broken down in the body it forms a poisonous chemical called acetaldehyde which in small amounts can be mopped up by the body.

But in larger quantities it can damage the body’s stem cells – the ‘master cells’ responsible for generating new cells. This increases the chances that they will go rogue and form cancerous tumours.

It has been estimated that almost 6 per cent of all cancer deaths worldwide could be attributed to alcohol. In the UK it is linked to 12,800 cases of cancer a year, or 4 per cent of total cancer cases. Of these, 3,200 breast cancer cases are caused by alcohol, says Cancer Research UK.

Even light drinking can slightly raise a woman’s risk of breast cancer, the NHS advises. Heavy drinkers face a greater risk of mouth and throat cancer, cancer of the voice box, liver and colorectal cancers.

The latest study, published in Nature, used mice to show how alcohol exposure led to irreparable genetic damage in stem cell DNA. A team at the Medical Research Council Laboratory of Molecular Biology, Cambridge, gave diluted alcohol – chemically known as ethanol – to the animals.

They analysed the DNA in the mice to examine the damage caused by acetaldehyde, known to be cancer-causing although the mechanism by which it works was not understood. They found acetaldehyde breaks and damages DNA within blood stem cells, permanently altering DNA sequences in these cells.

Lead author Professor Ketan Patel 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.’