It found that heavy drinkers are at the highest risk, but even low to moderate drinkers are more likely to get certain cancers than non-drinkers.
The review of evidence, published in the journal Addiction, also says studies claiming alcohol can help protect against heart disease should be treated with scepticism.
Health experts say the review strengthens the need to increase public awareness that drinking alcohol is a cause of cancer.
The new analysis by Professor Jennie Connor, PhD, of the University of Otago in Dunedin, New Zealand, examined studies on alcohol and cancer over the last 10 years.
It finds sufficient evidence to conclude that drinking increases the risk for areas of the body that come into direct contact with alcohol and where it may damage DNA, which is a known cause of cancer. The seven areas are:
• Mouth and throat
• Larynx, or voice box
While previous reviews have only been able to note a link between alcohol and cancer, the latest examination of the most recent research is strong enough to say that alcohol is a cause of these cancers, according to the analysis.
“There is strong evidence that alcohol causes cancer at seven sites, and probably others,” Connor writes.
“From a public health perspective, alcohol is estimated to have caused approximately half a million deaths from cancer in 2012; 5.8% of cancer deaths world-wide. The highest risks are associated with the heaviest drinking, but a considerable burden is experienced by drinkers with low to moderate consumption.”
The review also found some evidence to show that stopping drinking could reverse the risk of throat, larynx, and liver cancers.
Professor Dorothy Bennett, PhD, director of the Molecular and Clinical Sciences Research Institute at St. George’s, University of London, comments in a statement: “Alcohol enters cells very easily, and is then converted into acetaldehyde, which can damage DNA and is a known carcinogen.
“It’s not clear that there are any new implications” from the analysis, since health experts already recommend drinking in moderation, Bennett says. But, she says, it could strengthen support for the existing message.
Earlier this year, chief medical officers in the United Kingdom issued new guidance, warning that any amount of alcohol increases the risk of getting a range of cancers. They admitted that the risks were not fully understood when previous advice was issued in the mid-1990s.
“This important review reinforces the need for the public to be made aware of the causal link between alcohol and cancer,” Colin Shevills, from the Alcohol Health Alliance UK, says in a statement. “Research shows that only around 1 in 10 people are currently aware of the alcohol-cancer link.
“People have the right to know about the impact of alcohol on their health, including its link with cancer, so that they can make informed choices about how much they drink.”
For its part, the American Cancer Society recommends that people who drink alcohol limit themselves to no more than two drinks per day for men and one drink per day for women.
“Alcohol use has been linked to several types of cancer and other health risks, but this is complicated by the fact that low-to-moderate alcohol intake has been linked with a lower risk of heart disease,” the cancer society says on its website. “Still, lowering the risk of heart disease is not a compelling reason for adults who don’t drink alcohol to start.”