East Asians who have an enzyme deficiency that makes them flush when consuming alcohol appear to be at high risk of developing esophageal cancer if they drink heavily, according to a study from the U.S. National Institute on Alcohol Abuse and Alcoholism (NIAAA) and Japan’s Kurihama Alcohol Center.

Some people of East Asian descent have a deficiency of the aldehyde dehydrogenase 2 (ALDH2) enzyme, which is involved in alcohol metabolism. People with low levels of the enzyme typically experience facial flushing, nausea, and rapid heartbeat when they drink.

However, individuals who have one copy of the defective gene rather than two may become intolerant to the negative effects of acetaldehyde, an alcohol metabolite that is normally broken down by ALDH2. Left unchecked, acetaldehyde can cause DNA damage and other cancer-related problems.

“Cancer of the esophagus is particularly deadly, with five-year survival rates ranging from 12 to 31 percent throughout the world. And we estimate that at least 540 million people have this alcohol-related increased risk for esophageal cancer,” said study author Philip J. Brooks, Ph.D. “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.”

The study is published in the March 24, 2009 issue of the journal PLoS Medicine.