People who experience reddening of the face when drinking alcoholic beverages are at increased risk for cancer of the esophagus, the tube that passes food from the mouth to the stomach, according to a report in the journal PLoS Medicine.

The alcohol flushing response, which is common among people in East Asia, is due primarily to an inherited deficiency of an enzyme called aldehyde dehydrogenase 2, which is found throughout the body, especially in the liver.

"In view of the approximately 540 million aldehyde dehydrogenase 2-deficient individuals in the world, many of whom now live in Western societies, even a small percent reduction in esophageal cancers due to a reduction in alcohol drinking would translate into a substantial number of lives saved," say lead author Dr. Philip J. Brooks, National Institute on Alcohol Abuse and Alcoholism in Rockville, Maryland, and his associates.

About one third of people from Japan, China, and Korea have a genetic mutation that reduces body levels of aldehyde dehydrogenase 2. Since there are two copies of every gene for enzymes in the body, it is possible that a person can have this mutation in one, both, or neither copy of the aldehyde dehydrogenase 2 gene.

People with the this mutation or change in both copies of the gene have no detectable aldehyde dehydrogenase 2 activity, and the intensity of their response to alcohol — characterized by facial flushing, nausea, and a fast heartbeat — is so intolerable that they don't drink. Since regular alcohol use is known to promote esophagus cancer, these individuals are actually at reduced risk for the disease.

People with the change in just one copy of the gene have limited aldehyde dehydrogenase 2 activity, so their response to alcohol is less severe. They can therefore develop some tolerance to alcohol and can become heavy drinkers. It is these individuals that are at particularly high risk for esophagus cancer.

To identify those with aldehyde dehydrogenase 2 deficiency, they recommend that physicians ask patients of East Asian descent whether they have ever experienced facial flushing after drinking.

For younger patients who may not know, they advise an ethanol patch test, in which a pad with 70 percent alcohol is taped to the inner surface of the upper arm for 7 minutes. A positive result appears as redness after the patch is removed.

Aldehyde dehydrogenase 2-deficient patients should be informed of their increased risk, which is further increased by smoking, and counseled to limit alcohol use, the authors maintain.

Those at high risk because of moderate or heavy alcohol use should undergo endoscopy to detect esophageal cancer at a treatable stage.