By CLAIRE BATES
Drinking alcohol can increase your risk of cancer because ethanol is itself a carcinogen on certain parts of the body, scientists have found.
Researchers said they found that when ethanol is broken down by the body, it can cause DNA damage that may lead to dangerous changes to the cells.
The U.S team from the National Institute on Alcohol Abuse and Alcoholism in Maryland, used human cells engineered to produce an enzyme that is found in liver and breast tissue.
They exposed the cells to a concentration of alcohol similar to blood alcohol levels attained after having a few drinks on a night out.
The results confirmed that the alcohol (ethanol) was being converted to acetaldehyde, causing DNA damage and switching on the cell's DNA repair genes.
Study author Philip J Brooks, said: 'Although the link between drinking alcohol and certain types of cancers was first established in the 1980s the existence of such a relationship did not prove that alcohol itself caused the cancers.
'More recent evidence, however, has confirmed that alcohol - or more specifically, ethanol - is carcinogenic to humans at several sites in the body.'
Dr Brooks said the carcinogenic role of acetaldehyde came to light after East Asians were found to have an elevated risk of oesophageal cancer.
He said: 'In most people, acetaldehyde is quickly converted to acetate, a relatively harmless substance, by an enzyme called ALDH2.
'However, approximately 30 percent of East Asians are unable to metabolize alcohol to acetate due to a genetic variant in the ALDH2 gene, and have a greatly elevated risk of oesophageal cancer from alcohol drinking.'
He added: 'While our work is consistent with a role for acetaldehyde in alcohol related liver and breast cancer, more studies in animals and humans will be necessary to prove such a role.'
Oliver Childs, senior science information officer at Cancer Research UK, said: 'We've known for some time that alcohol is linked to several cancers, and it's likely that it causes different types of cancer in different ways.
'This work takes us a step closer to understanding one of the ways in which alcohol contributes to the development of breast and liver cancers - it will be interesting to see if this lab work translates into studies in people.'
The study was published in Alcoholism: Clinical & Experimental Research.