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 each year – 4 per cent of total cancer cases. Of these, 3,200 cases of breast cancer are caused by alcohol, according to 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 mice.
They analysed the DNA in the mice to examine the damage caused by acetaldehyde.
Acetaldehyde has long been known to be cancer-causing. But the mechanism by which it works had not been known.
They found acetaldehyde breaks and damages DNA within blood stem cells, permanently altering the DNA sequences within these cells. The chemical caused breaks in both strands of the DNA ‘double helix’, causing them to become jumbled up.
Alcohol isn’t thought to cause blood cancers, but the same mechanism is thought to apply to stem cells in other organs of the body. 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.’
The body can dispose of acetaldehyde by producing enzymes that break the chemical down.
Another protective mechanism is a variety of DNA repair systems which, most of the time, allow cells to fix and reverse different types of damage.
But there are limits to how much damage can be repaired, and in some people the repair process is faulty.
Professor 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 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.’
Cancer prevention expert Professor Linda Bauld, of Cancer Research UK which part-funded the study, said: ‘This thoughtprovoking research highlights the damage alcohol can do to our cells – costing some people more than just a hangover.
‘We know 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.’
‘Defence mechanisms’