Alcohol flush gene could reveal oesophageal cancer risk
People who lack an enzyme that causes their skin to flush when they drink alcohol may be more likely to develop oesophageal (gullet) cancer, even if they only drink moderately, a team of US and Japanese scientists have warned.
The deficiency, which affects the aldehyde dehydrogenase 2 (ALDH2) enzyme, is most frequent among people of east Asian descent.
ALDH2 plays an important role in the breakdown of alcohol, which the body initially converts into a chemical called acetaldehyde.
Acetaldehyde chemical is capable of damaging DNA and is usually broken down rapidly into a non-toxic chemical called acetate by the ALDH2 enzyme.
A small number of people inherit two copies of a 'faulty' variant of the ALDH2 gene - which makes the aldehyde dehydrogenase enzyme. They are unable to break down acetaldehyde effectively as the enzyme does not work properly. They have such severe symptoms after drinking alcohol - including facial flushing, nausea, and rapid heartbeat - that they are only able to consume very small amounts.
Other people, who inherit a single copy of the faulty gene variant, are often able to tolerate the unpleasant effects of acetaldehyde - but because they still break the chemical down more slowly than normal people, the chemical accumulates in their bodies.
Writing in the journal PLoS Medicine, scientists at the US National Institute on Alcohol Abuse and Alcoholism (NIAAA) and the Kurihama Alcohol Centre in Japan reviewed the evidence that suggested whether people with one copy of the faulty gene - who account for around eight per cent of the world's population - may be particularly at risk of oesophageal cancer because of the DNA-damaging effects of acetaldehyde.
They point to a series of epidemiological studies showing that people with one copy of the faulty gene are between six and ten times more likely to go on to have oesophageal cancer than those with 'normal' copies of the gene who drink a similar amount of alcohol.
Among people with one copy of the faulty gene, those who typically drank 33 alcoholic beverages per week were found to be 89 times more likely to develop oesophageal cancer than those who do not consume alcohol.
"It is very important for clinicians who treat patients of east Asian descent to be aware of the risk of oesophageal cancer from alcohol consumption in their patients who exhibit the alcohol flushing response, so they can counsel them about limiting their drinking," said Dr Kenneth Warren, acting director of the NIAAA, whose findings are published.
First author Dr Philip Brooks, from the NIAAA's Laboratory of Neurogenetics, noted that oesophageal cancer has a relatively poor survival rate compared with other cancers.
"We estimate that at least 540 million people have this alcohol-related increased risk for oesophageal cancer," he revealed.
"We hope that, by raising awareness of this important public health problem, affected individuals who drink will reduce their cancer risk by limiting their alcohol consumption."
Oliver Childs, senior science information officer at Cancer Research UK, said: "We know that drinking alcohol increases the risk of several different cancers, and that the more you cut down on your drinking, the more you reduce your cancer risk. This research helps us better understand how our environment and genes work in tandem to influence our risk of cancer."