Alcohol consumption was linked to at least 740,000 new cases of seven different cancers in 2020, according to a study published in Lancet Oncology, which is among the first studies to quantify the cancer risk associated with drinking alcohol, Susan Brink reports for NPR's "Goats and Soda."

Infographic: Envisioning the future of cancer care

Study details

For the study, researchers looked at three data sets:

• Estimates of global alcohol consumption;
• Cancer risks from alcohol; and
• Estimates of global incidence of alcohol-linked cancers.

The researchers found that alcohol consumption was linked to at least 741,300 new cases of seven different types of cancer worldwide, accounting for 4% of total cases of those cancers. The cancers examined included:

• Esophageal cancer;
• Mouth cancer;
• Larynx cancer;
• Colon cancer;
• Rectum cancer;
• Liver cancer; and
• Breast cancer.

Men accounted for roughly 75% of the alcohol-related cancer cases—or 568,700 total cases—while women accounted for the remaining  172,600 cases. According to the study, cancers of the esophagus (189,700 cases), liver (154,700 cases), and breast (98,300 cases) "contributed the most cases."

The researchers also found that an individual's cancer risk increased with the amount of alcohol consumed. However, even drinking two or fewer alcoholic drinks per day—considered moderate drinking, according to the study—accounted for an estimated 14% of alcohol-related cancers.

How alcohol may affect cancer risk

According to the study, alcohol may contribute to cancer risk via several mechanisms.

For instance, ethanol—which is the form of alcohol in beer, wine, and liquor—breaks down into acetaldehyde, which is a known carcinogen. Acetaldehyde can also act as "a solvent for other carcinogenic agents," including those found in tobacco, the researchers wrote, meaning those who both smoke and drink alcohol are at an even greater risk of cancer.

Alcohol can also increase hormone levels, the researchers wrote, which leads to increased cell division and more opportunities for cancers to develop. In addition, alcohol reduces the body's ability to absorb nutrients that can protect against cancer, including folate and vitamins A, C, D, and E, Brink reports.

Discussion

According to Rumgay, this study is among the first to quantify the cancer risks associated with different levels of drinking.

"Fewer than one in three Americans recognize alcohol as a cause of cancer," Rumgay said. "That's similar in other high-income countries, and it's probably even lower in other parts of the world."

In an accompanying commentary, Amy Justice, a professor of medicine and public health at Yale University, agreed with the study's conclusions and offered strategies to reduce the number of alcohol-related cancers.

As a doctor, Justice said, she thinks about what she can say to a patient in a one-on-one setting to encourage them to reduce their alcohol consumption. "There's pretty good data that you can get people to decrease their alcohol consumption with brief motivational information," Justice said.

That could mean teaching health care providers to talk with patients about alcohol use when discussing sleep or memory problems, or if they have the beginning signs of liver disease, she said.

"You tailor the information to the personal concerns of the patient in front of you," Justice said. (Brink, "Goats and Soda," NPR, 7/17).