Even Moderate Alcohol Use Can Increase Cancer Risk

It’s been well-noted that excessive alcohol consumption can lead to a slew of health effects, including an increased risk of multiple types of cancers, but what about the effects of moderate drinking?

This was the question asked — and answered — by a team of researchers at Harvard University’s T.H. Chan School of Public Health in Boston, who surprisingly found that the results differed between men and women.

“Heavy drinking has been linked to increased risk of several cancers, including cancer of the colon, female breast, oral cavity, pharynx, larynx, liver and esophagus, and possibly to a higher risk of cancer of the stomach, pancreas, lung and gallbladder,” Edward Giovannucci, M.D., S.D., professor of nutrition and epidemiology and study author, said in an interview with CURE.

The association between light to moderate drinking, which the Dietary Guidelines for Americans — nutrition advice published by The U.S. Department of Health and Human Services and the U.S. Department of Agriculture every five years — describes as up to one alcoholic drink per day for women, and up to two drinks per day for men, was less clear.

“We found that light to moderate drinking was associated with minimally increased risk of overall cancer,” Giovannucci said, noting that there was a difference in increased cancer risk between genders.

The risk of alcohol-related cancers was not appreciably increased for men who were light or moderate drinkers and nonsmokers, Giovannucci explained. However, female nonsmokers had an increase of alcohol-related cancer — mainly breast cancer — after consumption of up to one alcoholic drink a day. For the women who had a drink a day, the risk increase was about 15 percent.

“For women who have a family history of breast cancer, because of their higher risk, this increased risk may be even more important,” Giovannucci said.

Science has yet to pinpoint what, exactly, it is about alcohol that can lead to a higher cancer risk, but Giovannucci said that it likely has to do with the compound that alcohol breaks down to, acetaldehyde, which can be toxic.

“When we drink alcohol, it gets absorbed in the stomach and goes into the blood. Of course, people are aware that it can reach the brain,” he said. “Likewise, it can reach other organs. The way alcohol gets metabolized or break down in different organs may influence if it affects cancer risk.”

For example, Giovannucci said, evidence suggests that the bacteria in the large intestine breaks down alcohol pretty quickly, leading to high amounts of acetaldehyde, which may increase risk of cancer in that area.

Giovannucci said that it is crucial that more research be done in this field, carefully laying out the risks and benefits of light and moderate alcohol use.

“There is some evidence that light to moderate alcohol may reduce risk of heart disease and diabetes. Interestingly, this potential benefit may be stronger in women than men,” he said. “Thus, despite their higher risk of breast cancer due to alcohol, the pros and cons of alcohol for women are still unclear. Yet, at higher levels of drinking, we know that the negative effects are important.”