“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,” Surgeon General Vivek Murthy warned in his advisory issued Friday. “Yet the majority of Americans are unaware of this risk.” 

Murthy noted cancer risk increases as alcohol consumption increases. For certain cancers — including breast, mouth and throat cancers — he said evidence shows that the risk of developing cancer may start to increase around one or more drinks per day. 

The advisory comes amid a major debate in the scientific community about whether or how much alcohol consumption is safe for adults, and ahead of an update to the influential federal Dietary Guidelines. 

The 2020-2025 Dietary Guidelines recommend limiting intake to two drinks or less a day for men and one drink or less a day for women, and that overall “drinking less is better for health than drinking more.” 

But how much alcohol is safe? Experts say that’s hard to determine.

The World Health Organization says there is no “safe amount of alcohol consumption.” 

A report in December from the National Academies of Sciences, Engineering, and Medicine concluded that moderate drinking may be associated with lower risks of cardiovascular disease, as well as all-cause mortality.  

Yet it also found moderate drinking was associated with a higher risk of certain cancers, mainly breast cancer in women. 

Howard Ross, chief of surgery at Hackensack University Medical Center in New Jersey, said the link between alcohol and cancer isn’t an all-or-nothing proposition. The value of a warning label is that it can inform the public, he said.

“If patients know that indeed there is a risk, then they can modify their behavior to optimize their health,” he said. “The question isn’t ‘is there a safe level’ but ‘what is the safest level.’”  

Ross said the risk is different for different types of cancer, as well as a person’s other health factors.  

“So having a healthy diet, not being obese, exercising, not using tobacco products, staying away from UV radiation, those are all modifiable risk factors. So alcohol becomes one of those,” Ross said.

“If you had a significant concern about cancer development, and you’re in the group that wants to do everything you can, you might want to refrain from alcohol.”