Boozy blush signals cancer risk for East Asians: study

Turn a bit red when you drink a mere half bottle of beer? If you're of East Asian descent, consider that a warning: You may be at higher risk of alcohol-caused esophageal cancer.

Researchers reported the link Tuesday in hopes of increasing awareness that the inherited flushing trait — found in about a third of people from Japan, China and Korea — offers valuable health information.

Alcohol is a known risk factor for a variety of cancers, including esophageal, and heavier drinking is considered riskier than light drinking.

Lots of people turn slightly red if they imbibe too much. At issue here is facial flushing from a small amount of alcohol.

It's due to a deficiency in an enzyme that helps metabolize alcohol, called ALDH2.

People with a severe deficiency of the enzyme usually don't drink because it makes them feel too bad; in addition to flushing they feel nausea and a rapid heartbeat.

But people with a partial deficiency — they inherited one bad copy of the enzyme-producing gene instead of two — may put up with the flushing.

A series of studies by Dr. Akira Yokoyama of Japan's Kurihama Alcohol Centre found that those people are six to 10 times more likely to develop esophageal cancer than people who drink a comparable amount but aren't enzyme-deficient.

"Somehow the message just hadn't gotten out," said Dr. Philip Brooks, who researches alcohol and cancer at the U.S. National Institutes of Health.

So he paired with Yokoyama and others to review the link for PLoS Medicine, a journal published by the Public Library of Science.

Without enough of that enzyme, alcohol breaks down into a DNA-damaging chemical similar to formaldehyde but it doesn't go the next step and turn into yet another chemical that's non-toxic, said Brooks. Don't drink, and the flushers aren't at increased risk.

Esophageal cancer is fairly rare, but it's also hard to treat. Worldwide, anywhere from 12 per cent to a third of people who develop it survive five years.

Up to eight per cent of the world's population has the enzyme deficiency, meaning if even a small number of the at-risk avoided alcohol, esophageal cancer deaths could drop substantially, the review concluded.

In North America, most esophageal cancer is a type called adenocarcinoma that is linked to chronic, severe heartburn. The flushing-linked type is squamous cell carcinoma, less common here than abroad.