The US Surgeon General Dr Vivek Murthy took to X, formerly Twitter, to say that he was issuing an advisory on the link between cancer and alcohol consumption. "Alcohol is the 3rd leading preventable cause of cancer in the U.S., contributing to about 1,00,000 cancer cases and 20,000 cancer deaths each year," he wrote in a series of posts.

“Consuming any type of alcohol – beer, wine, or spirits – increases the risk for at least seven types of cancer, including cancers of the breast for women, colorectum, esophagus, liver, mouth, throat, and voice box (larynx)," he posted while adding that despite the links only 45% of Americans knew of the risks.

The risk of cancer is directly linked to the amount of alcohol a person consumes. A key factor is the total alcohol intake over time, with the risk increasing as consumption rises. For certain cancers—such as breast, mouth, and throat cancer—even light drinking, around one drink or less per day, has been shown to elevate the risk.

The advisory, which is called “Alcohol and Cancer Risk 2025” and was issued earlier this month, emphasised that understanding the risk requires comparing the likelihood of developing cancer among those who consume alcohol to those who do not.

The advisory said that in 2019 alone, an estimated 96,730 cancer cases in the US were related to alcohol consumption, which would translate to about 10 lakh cases in 10 years. "Alcohol consumption is the third leading preventable cause of cancer in the United States, after tobacco and obesity," according to the advisory.

The largest burden of "alcohol-related cancers" was breast cancer, where they said about 16.4 per cent of the total breast cancers in the country were linked to alcohol consumption.

Two decades of research

The advisory pointed out that multiple studies and reviews over the last two decades have shown a "significant relationship between alcohol consumption and increased cancer risk."

“A global meta-analysis of 572 studies examining data from 4,86,538 cancer cases resulted in findings consistent with this conclusion,” the advisory said.

The cited study shows that the risk of a woman developing any alcohol-related cancer increased from "approximately 16.5% (about 17 out of every 100 individuals) for those who consume less than one drink per week, to 19.0% (19 out of every 100 individuals) for those who consume one drink daily on average to approximately 21.8% (about 22 out of every 100 individuals) for those who consume two drinks daily on average."

How does alcohol cause cancer?

According to the advisory, alcohol causes cancer in four ways.

"First, alcohol breaks down into acetaldehyde in the body. Acetaldehyde is a metabolite that causes cancer by binding to DNA and damaging it. When DNA is damaged, a cell can begin to grow uncontrollably and create a cancerous tumour," it said.

It also highlighted that alcohol also creates "reactive oxygen species," which causes inflammation and damages one's DNA, proteins and fats.

"Third, alcohol alters hormone levels (including estrogen), which can play a role in the development of breast cancer," it said while adding that carcinogens from other sources like tobacco smoke can also dissolve in alcohol and be easily absorbed, "increasing the risk for mouth and throat cancers."

What should be done?

The advisory suggested multiple steps and actions that can be taken to help reduce the burden of alcohol-related cancers in the country, including updating the Surgeon General’s health warning label on alcohol to include a warning about the cancer risk linked to alcohol consumption and making it more visible.

It also called for reassessing the recommended alcohol limits based on the latest research on alcohol and cancer.

The advisory encouraged stronger education efforts to help people understand that alcohol causes cancer.

It also recommended informing patients in healthcare settings about the connection between alcohol and cancer risk. "Promote the use of alcohol screening and provide brief intervention and referral to treatment as needed," it advised.

It also said that alcohol is a major, modifiable cancer risk factor and urged the inclusion of alcohol reduction strategies in cancer prevention programs.

For individuals, it advised being mindful of how alcohol consumption increases cancer risk when deciding whether or how much to drink. "Cancer risk increases as you drink more alcohol," it underlined.