For many people, drinking alcohol—a glass of wine with dinner or cocktails with friends after work—is an enjoyable part of life. But drinking alcohol, especially heavy drinking, can cause health problems, including increased risk of several types of cancer.
“Alcohol is a largely unrecognized risk factor for cancer,” said Abenaa Brewster, M.D., a professor in the Department of Clinical Cancer Prevention at The University of Texas MD Anderson Cancer Center. “People are very aware of the relationship between smoking and cancer, but they’re not quite as aware of the relationship between alcohol and cancer.” To raise awareness about the link between alcohol and cancer, Dr. Brewster and her colleagues from the American Society of Clinical Oncology published a position paper on the topic in the January 2018 issue of the Journal of Clinical Oncology.
The position paper points out that the World Health Organization classifies alcohol as a carcinogen (cancer-causing agent). This classification was made on the basis of research showing associations between alcohol consumption and several types of cancer. For some of these cancers, even moderate alcohol consumption increases the risk.
Alcohol content and consumption
To discuss how drinking alcohol affects cancer risk, it is first necessary to define how much alcohol is in a drink. According to the Dietary Guidelines for Americans by the U.S. Department of Health and Human Services, a standard alcoholic drink contains 14 grams (g), or 0.6 ounces (oz), of alcohol. This is roughly the amount of alcohol found in 12 oz of beer, 5 oz of wine, or 1.5 oz of 80-proof (40% alcohol) liquor.
“We want people to be aware of serving sizes,” Dr. Brewster said. “Hurricanes and other alcoholic drinks that come in massive glasses are more than one serving.”
The Dietary Guidelines define moderate alcohol consumption as one or fewer drinks per day for women and two or fewer drinks per day for men. Heavy drinking is defined as four or more drinks per day, or more than seven per week, for women and five or more drinks per day, or more than 14 per week, for men.
Binge drinking, which causes half of alcohol-related deaths, is defined as four or more drinks for women and five or more for men within 2 hours. “We don’t know what effect binge drinking has on cancer risk, but we know the effect of binge drinking overall is bad,” Dr. Brewster said.
Types of cancer caused by alcohol
Head and neck cancers. Moderate drinkers have double the risk of a particular type of cancer, squamous cell carcinoma of the esophagus, as non-drinkers; and heavy drinkers have four times the risk. Some people have an inherited trait that makes it difficult for their bodies to process alcohol; these people have an even higher risk of esophageal squamous cell carcinoma if they drink.
Compared with nondrinkers, heavy drinkers have nearly three times the risk of cancer of the larynx (voice box) and more than five times the risk of cancers of the oral cavity (mouth) and pharynx (the part of the throat that leads from the mouth to the esophagus).
Tobacco use further increases the risk of head and neck cancers in those who drink alcohol.
Liver cancer. Moderate drinkers have a slightly higher risk of liver cancer than do nondrinkers, and heavy drinkers have double the risk. Chronic liver diseases such as hepatitis B or C infections can make the effect of alcohol even worse.
Colorectal cancer. Heavy drinkers have nearly one and a half times the risk of colorectal cancer as nondrinkers.
Breast cancer. Women who drink alcohol moderately have a slightly higher risk of breast cancer than do nondrinkers; and heavy drinkers have more than one and a half times the risk. A large study in the United Kingdom found a 12% increase in breast cancer risk for every 10 g of alcohol consumed daily.
Benefits vs. risks
Understanding the risks of alcohol use can be difficult because moderate alcohol consumption has some health benefits. Some studies have linked alcohol to reduced risks of non-Hodgkin lymphoma and kidney cancer. And red wine consumption is known to increase levels of “good” cholesterol (high-density lipoproteins, or HDL), which promotes heart health. However, the Dietary Guidelines, the American Cancer Society, and the American Heart Association all state that nondrinkers should not start drinking alcohol for its perceived health benefits, and all these groups warn against heavy alcohol consumption.
“If you don’t drink, you shouldn’t start,” Dr. Brewster said, adding that people who already drink should limit their alcohol consumption to moderate levels. “Social drinking is increasing among young adults, and we’re very concerned that alcohol-related cancer will become an issue for them down the line.”
OncoLog, April 2018, Volume 63, Issue 4