With the U.S. surgeon general calling for cancer warnings to be added to alcoholic beverage labels, many Americans may be wondering how many, if any, drinks can be consumed safely.
Dr. Vivek Murthy’s advisory, released on Friday, noted that alcohol consumption is the third-leading preventable cause of at least seven types of cancer, after tobacco use and obesity.
“Alcohol is a well-established, preventable cause of cancer responsible for about 100,000 cases of cancer and 20,000 cancer deaths annually in the United States," Murthy said in a statement.
The seven types of cancer linked to alcohol include breast, colorectal, esophageal, liver and mouth cancers. Breast cancer is the leading cause of alcohol-related cancer death in women; in men, it's liver and colorectal cancers.
Many people are unaware of this link, however. The surgeon general report stated that less than half of Americans know that drinking alcohol can increase cancer risk; a 2022 study estimated that it's less than one-third. And even though research has accumulated in recent years supporting this link, there hasn't been a corresponding increase in awareness.
Instead, about 72% of U.S. adults say they consume at least one drink a week, according to the surgeon general's report. "The more alcohol consumed, the greater the risk of cancer," the report added.
Many leading public health agencies consider alcohol to be a top cancer-causing agent. The World Health Organization's International Agency for Research on Cancer considers it a Group 1 carcinogen, the highest level, alongside asbestos and formaldehyde. The U.S. Centers for Disease Control and Prevention and the National Institutes of Health’s National Cancer Institute also agree on the link between alcohol and at least seven types of cancer.
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So does that mean you should cut out drinking all together? Is there any amount of alcohol that experts believe is safe? Here's what to know.
How does alcohol cause cancer?
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There are several known ways alcohol causes cancer, Jiyoung Ahn, Ph.D., a cancer epidemiologist and associate director of population research at the NYU Langone Perlmutter Cancer Center in New York City, tells TODAY.com.
Alcohol is converted in the body to acetaldehyde, which directly damages DNA, she explains, adding that "alcohol also induces oxidative stress, which also damages DNA.”
What’s more, alcohol can aggravate other cancer risk factors. For example, if you’re a smoker who drinks, the increase in risk will be larger than it would be if you just added the risks of each together. “The smoking carcinogens are more easily absorbed into the body,” Ahn says.
Last, alcohol consumption can affect hormone levels, which may increase the risk of breast cancer, according to the surgeon general report.
How many drinks a week will increase your cancer risk?
It’s not clear yet whether there’s any amount of alcohol that won’t raise cancer risk at all, as different studies have come to different conclusions. (A recent major report even linked moderate drinking to a lower risk of death.)
Murthy told NBC News that there's no “magic level” of safe alcohol consumption for the entire population. “What we do know is that less alcohol consumption means less cancer risk.”
"Heavy drinking" in particular can increase the risk of certain cancers, Dr. Walter Willett, a professor epidemiology and nutrition at the Harvard T.H. Chan School of Public Health and a professor of medicine at the Harvard Medical School, tells TODAY.com.
“We knew quite a long time ago that ... three, four, five drinks a day increased the risk of upper (gastrointestinal) cancers,” Willett says. He adds that just two drinks a day can increase the risk of cancer by 25% compared to non-drinkers.
But what about drinking even less than that?
Whether there's an increase in cancer risk with smaller amounts of alcohol depends on the type of cancer, Willett says.
“For breast cancer, we see a small increase in risk — about 15% compared to non-drinkers — with three or four drinks per week, or about half a drink per day," he explains, adding that “breast tissue seems to be particularly sensitive to alcohol.”
"For most other types of cancer, we don’t see much of an increase until we get close to two drinks per day. For some types of cancer, especially esophageal and oral cancers, smoking multiples the risk.”
Two to three drinks a week is probably OK, Willett suggests. “My advice is to get a very good bottle of wine and enjoy every sip.”
On the other hand, the surgeon general uses less than one drink a week as its baseline for cancer risk in its report, Dr. Joseph Sparano, chief of hematology and medical oncology and deputy director of the Tisch Cancer Institute at the Icahn School of Medicine at Mount Sinai, points out.
The amount of alcohol least likely to increase cancer risk "seems to be less than one drink per week," Sparano tells TODAY.com.
He also says that the current dietary guidelines for alcohol consumption — one drink or less a day for women and two or less for men — actually seem to increase cancer risk.
“Drinking may explain some of the increased cancer risk we are seeing in young people,” Sparano adds. “Cancers in people under the age of 50 have been increasing at a rate of 1-2% per year over the last 15 years.”
Are certain types of alcohol higher risk for cancer?
Experts say it doesn’t seem to matter what kind of alcohol people consume, whether that's beer, wine or spirits. What matters is the amount.
For example, a seminal 1983 study found that, more than any other dietary habit, “beer, wine and liquor raised the risk (of cancer) the most,” Willett says.
The surgeon general report shared a similar conclusion: "The data in humans on alcohol and health show a strong association between drinking alcohol and increased cancer risk, regardless of the type of alcohol."
Does cutting back on alcohol decrease cancer risk?
Cutting back on alcohol may decrease cancer risk if people reduce consumption by the time they hit mid-life, Mary Beth Terry, Ph.D., associate director of the Herbert Irving Comprehensive Cancer Center and a professor of epidemiology at the Mailman School of Public Health at Columbia University, tells TODAY.com.
“A recent meta-analysis suggested that if you do reduce your drinking, you could reduce the risk of the most common type of breast cancer," Terry says.
Dr. Wei Zheng, director of the Vanderbilt Epidemiology Center at Vanderbilt University Medical Center in Nashville, told NBC News that "some damage (from alcohol) can be permanent, (but) some can be reversed. ... Cutting down on drinking will certainly reduce risks in the future.”
While it’s good that the surgeon general suggested that labeling on products be changed, we know from the example of smoking that that won’t be enough to get people to cut back or quit, Terry says, adding that public health agencies need to mount marketing campaigns to educate the public just as they did for smoking.
This story first appeared on TODAY.com. More from TODAY:
