An opinion piece published in the scientific journal Addiction in July gathers evidence to argue that alcohol is a direct cause of cancer in several areas of the body.
The article reviews 10 years’ worth of studies from several organizations, including the World Cancer Research Fund, the American Institute for Cancer Research and the International Agency for Research on Cancer.
And its conclusions are dire.
Nearly 6 percent of cancer deaths worldwide can be linked to alcohol, including in people who drink light to moderate amounts of alcohol, according to author Jennie Connor, a professor of epidemiology at the University of Otago in New Zealand. “From a public health perspective,” she writes, “alcohol is estimated to have caused approximately half a million deaths from cancer in 2012.”
Connor concludes that there is a strong link between alcohol consumption and cancer in specific areas of the body, such as the liver, colon, esophagus and female breast. She says there are also causal contributions in other areas such as the prostate, pancreas and skin.
How alcohol causes cancer is not deeply understood, according to the article, but it is thought to depend on the “target organ.” For example, cancers of the throat, mouth and liver can be largely attributed to a carcinogenic compound called acetaldehyde. Salivary acetaldehyde levels have been found to reach high levels when drinking.
Breast tissue is another area that seems to be particularly susceptible to alcohol.
Connor noted the United Kingdom’s Million Women Cohort study, which found that women who drank 70 to 140 grams of alcohol per week experienced a 13 percent increase in breast cancer and a 5 percent increase in total cancer compared to those who drank less than 20 grams per week.
Unfortunately, the amount you drink might not matter all that much. While heavy drinkers have a higher risk of liver, colon and laryngeal cancer than light drinkers, Connor writes, all drinkers have the same risk of mouth, esophagus, breast and pharynx cancer.
Connor also acknowledges that some of the studies she reviewed show that those who drink light to moderate of alcohol have a reduced risk of developing cardiovascular disease than abstainers.
But many epidemiologists agree that research confirms alcohol actually causes cancer, Connor wrote, while the relationship between drinking and heart disease is not as conclusive.
For example, other lifestyle factors beyond alcohol consumption ― such as a person’s healthy behavior and demographic conditions ― typically put abstainers at a higher risk than those who moderately drink. Connor cites a 2005 study that showed 27 out of 30 risk factors for cardiovascular disease were more prevalent in abstainers than moderate drinkers.
“Promotion of health benefits from drinking at moderate levels is seen increasingly as disingenuous or irrelevant in comparison to the increase in risk of a range of cancers,” she wrote.
As a solution to alcohol-attributed cancer, Connor suggests everyone should reduce their alcohol consumption, not just heavy drinkers.
“Population-wide reduction in alcohol consumption will have an important effect on the incidence of [cancer], while targeting the heaviest drinkers alone has limited potential,” she wrote.
While the majority of the population readily accepts that smoking causes lung cancer, “alcohol’s causal role is perceived to be more complex than tobacco’s,” Connor wrote.
Getting people to stop drinking to prevent cancer, in the same way people stop smoking to prevent cancer, is not the focus of any significant push.
Connor also warns of the backlash that research such as her own may receive from alcohol companies.
“There will be orchestrated attempts to discredit the science and the researchers, and to confuse the public,” she wrote. “The stakes are high for alcohol industries when there is no argument, on current evidence, for a safe level of drinking with respect to cancer.”
Ultimately, alcohol is just one of many factors that can cause cancer, but Connor suggests reducing consumption or even partaking in a “dry period” as steps in the right direction to reduce your risk.
Correction: An earlier version of this article incorrectly identified Connor’s opinion article as a new study on alcohol’s link to cancer. In fact, Connor’s opinion piece reviews existing literature on the subject and does not present new data or conclusions. Language has been updated throughout.