By Nina Agrawal and Katie Mogg
The U.S. Public Health Service’s surgeon general cautioned late last week that even light or moderate drinking can heighten the risk of cancer.
In a recent report, Dr. Vivek Murthy, the surgeon general, stated that alcohol use is directly associated with at least seven cancer types, including those affecting the mouth, throat, larynx, esophagus, breast, liver, and colon and rectum. In 2020, there were 741,300 cancer cases linked to alcohol worldwide.
However, the public’s understanding of this connection is limited: Only 45% of Americans believe alcohol significantly influences the risk of cancer development, based on a 2019 national survey by the American Institute for Cancer Research.
Studies indicate that the more alcohol an individual drinks—especially with habitual consumption—the higher the cancer risk. This link pertains to all alcoholic beverages: beer, wine, and spirits.
Even what is commonly perceived as “light” or “moderate” drinking—up to one drink daily—can raise the risk of several cancers, including those of the mouth, pharynx, and breast.
“There is no safe amount of alcohol regarding cancer risk,” remarked Dr. Ernest Hawk, vice president and head of the division of Cancer Prevention and Population Sciences at the University of Texas MD Anderson Cancer Center.
Your consumption level significantly impacts your risk.
The surgeon general’s report characterizes a standard drink as containing 14 grams of alcohol—about what’s found in a 5-ounce glass of wine, a 12-ounce beer, or a 1.5-ounce shot of spirits. The report evaluated evidence on cancer associated with different consumption levels per day or week.
Fewer than one drink per week: Research examining very light drinking related to cancer is limited. Murthy’s report assessed what is termed absolute risk—or the probability of a specific outcome occurring over a certain time frame—of particular cancers at various drinking levels. It utilized data from an Australian study involving nearly a quarter-million adults published in 2020.
On average, the report revealed that approximately 17 out of 100 women who consumed one drink per week or less would develop alcohol-related cancers throughout their lives. About 11 out of 100 women would develop breast cancer, which is classified as alcohol-related. Research indicates that alcohol may increase estrogen levels, a hormone connected to breast cancer.
Men who drank less than one drink weekly had around a 10% probability of developing any alcohol-related cancer over their lifetimes.
Researchers categorized this group of “fewer than one drink per week” as the reference group for comparison against higher drinking levels. Similar to many studies, non-drinkers were not included to prevent the “sick quitter” effect, which occurs when a study’s findings are distorted by individuals who stopped drinking due to health issues.
One drink daily: For many years, it was commonly believed that consuming low or moderate amounts of alcohol benefited health, especially heart health. However, recent studies indicate that even one drink a day is associated with increased health risks.
The surgeon general’s report noted that the lifetime risk of developing any alcohol-related cancer rose to 19% (19 out of 100 women) for those consuming one alcoholic drink each day (seven drinks weekly). At this level, the lifetime risk of breast cancer climbed to 13.1%, or 13 out of 100 women.
According to Murthy’s report, around 11 out of 100 men who consumed one drink daily would develop an alcohol-related cancer during their lifespan.
Although the absolute increases in risk may seem minimal, they represent a significantly heightened relative risk compared to those who consume less alcohol.
A 2013 study published in the Annals of Oncology that specifically analyzed the connection between “light drinking” and cancer found that individuals who consumed up to one alcoholic beverage daily had a 30% higher risk of developing esophageal cancer, a 17% greater risk of developing cancers of the oral cavity and pharynx, and a 5% higher chance of developing breast cancer compared to non-drinkers.
Two drinks per day: At two drinks each day (14 weekly), the proportion of women likely to develop alcohol-related cancers throughout their lives increased from 16.5% (in the “less than one drink per week” category) to nearly 22%, based on the surgeon general’s report. The likelihood of developing breast cancer rose to 15.3%.
Among men drinking at this level, the chance of developing an alcohol-related cancer during their lifetime went up to 13%.
Four or more drinks daily: Heavily drinking—generally defined as four or more drinks each day—is linked not only to cancers of the mouth, oropharynx, larynx, esophagus, breast, and colorectal region but also to cancers of the liver, stomach, gall bladder, and pancreas.
A comprehensive meta-analysis comparing light, moderate, and heavy drinkers to non-drinkers and occasional drinkers found that heavy drinkers had more than double the relative risk of liver and gallbladder cancer compared to non-drinkers and occasional drinkers. Their risk of stomach, lung, and pancreatic cancer was approximately 15% to 20% higher.
Consuming four or more drinks within a two-hour span is defined as binge drinking for women, whereas five or more drinks qualify as bingeing for men. While binge drinking is associated with numerous harmful effects, most human studies have not differentiated the cancer risk between consuming large amounts in one sitting versus over several days, noted Dr. Timothy Naimi, director of the Canadian Institute for Substance Use Research at the University of Victoria. “This is a crucial area that requires future research.”
Other risk factors also contribute.
Although the report focuses on drinking levels, various other factors—such as sex, genetics, diet, and family history—also influence how alcohol affects cancer risk.
For example, women require less alcohol to harm their health compared to men, likely due to slower alcohol metabolism, which causes it to remain in their systems longer.
Individuals with genetic mutations or family histories that increase their susceptibility to these cancers begin with a higher baseline cancer risk, experts assert.
Certain behaviors and lifestyle choices may also amplify the risk of alcohol-related cancers. The combination of drinking and smoking cigarettes, for example, is known to heighten the risk of head and neck cancers, stated Elizabeth Platz, a cancer epidemiologist at Johns Hopkins Bloomberg School of Public Health. Additionally, consuming alcohol alongside poor dietary and exercise practices can further increase the likelihood of becoming overweight or developing obesity, another condition linked to cancer.
Cutting back on drinking reduces (some of) the risk.
A working group from the International Agency for Research on Cancer recently concluded that long-term abstaining or reducing alcohol intake correlates with a decreased risk of oral and esophageal cancer. However, it remains unclear whether or when reducing alcohol intake brings the risk down to baseline levels, according to the surgeon general’s report.
Naimi noted that even for individuals who drink heavily, slightly reducing their alcohol intake will yield long-term health benefits. “Less is better,” he emphasized.
