More than 700,000 new cases of cancer worldwide in 2020 were attributable to alcohol consumption, according to a population-based modeling study.

Men accounted for about three-quarters of these cancer cases, which most commonly affected the esophagus and liver, reported Harriet Rumgay, BSc, of the International Agency for Research on Cancer’s Cancer Surveillance Branch in Lyon, France, and colleagues.

And while heavy drinking patterns contributed most to these alcohol-related cancer cases, “we estimate that light to moderate drinking of the equivalent of around one or two alcoholic drinks per day was accountable for more than 100,000 cases of cancer in 2020,” wrote Rumgay and her colleagues in an article in The Lancet Oncology.

Even drinking 10 grams daily contributed 41,300 new cases of cancer in 2020.

As pointed out by the authors, alcohol is causally linked to multiple cancers, including cancers of the oral cavity, pharynx, larynx, esophagus, colon, rectum, liver, and breast – cancers that accounted for 6.3 million cancer cases, and 3.3 million deaths globally in 2020.

In their study, the authors established levels of alcohol intake per person, per country, using 2010 data from the Global Information System on Alcohol and Health (assuming a 10-year latency period between alcohol consumption and cancer development), and combined them with new cancer cases in 2020 to estimate the number of alcohol-associated cancers in each country.

Estimates for alcohol intake were based on data including alcohol production, tax and sales data, surveys, and tourist alcohol consumption. Rumgay and her colleagues then converted alcohol consumption estimates to the amount of alcohol consumed per day.

Rumgay and colleagues calculated that globally, there were an estimated 741,300 cases of new cancers (4.1%) that could be attributed to alcohol consumption in 2020, with males accounting for 76.7% of these cases.

Cancers attributed to alcohol included:

• Esophageal (189,000 cases)
• Liver (154,000)
• Breast (98,300)
• Colon (91,500)
• Rectal (65,100)
• Pharyngeal (39,400)
• Laryngeal (27,600)

The regions with the highest proportions of cancer cases that could be attributed to alcohol were Eastern Asia (5.7%) and Central and Eastern Europe (5.6%), while North Africa (0.3%) and Western Asia (0.7%) had the lowest proportion.

When separated into drinking categories the authors estimated that moderate drinking (up to 20 g/day — the equivalent of 1 to 2 drinks) contributed 103,100 (13.9%) new cases of cancer, while risky drinking (20-60 g/day — equivalent to 2 to 6 drinks) contributed 291,800 (39.4%) new cases and heavy drinking (>60 g/day — equivalent to >6 drinks) contributed 346,400 (46.7%) new cases.

The authors noted that the impact of the COVID-19 pandemic should be taken into account when considering health outcomes in 2020.

“The cancer incidence estimates for 2020 used in our study do not account for changes in the reporting of cancer due to disruptions caused by health systems closures and the concerns of individuals, among other reasons,” wrote Rumgay and her colleagues. They also pointed out that the pandemic might have affected drinking patterns, as was suggested by a study showing an increase in binge drinking in the U.K.

Rumgay and her colleagues also observed that, with the link between alcohol consumption and economic development, an increase in alcohol consumption is projected in countries such as China and India.

“With increases in alcohol consumption predicted until at least 2030 in several world regions, action must be taken to reduce the avoidable burden of cancer attributable to alcohol,” they urged.

In a commentary accompanying the study, Amy C. Justice, MD, PhD, of Yale University in New Haven, Connecticut, wrote that understanding the burden of cancer associated with alcohol use and how best to intervene is limited by an inability to get accurate measures of alcohol exposure.

For example, she noted that relying on commercial sales is problematic because a quarter of consumption occurs outside government-controlled channels. And self-report surveys underestimate alcohol use among heavy drinkers and persons with health conditions that are exacerbated by alcohol, such as HIV and hepatitis C infection.

“Unless we address limitations in measurement, we might be underestimating health risks, especially cancer risks, associated with alcohol,” she wrote. “This might be especially true among individuals who are most vulnerable. The sooner we start accurately measuring alcohol exposure, the sooner we can understand the true excess burden of cancer attributable to alcohol, and effectively intervene.”