Alcohol ‘directly causes’ seven forms of cancer, a New Zealand scientist is warning in a new controversial commentary that suggests drinking even low to moderate amounts is risky.
The medical community often talks about a “link” between cancer and drinking – this is a major upgrade linking the two.
“An association means there is a relationship of some kind between the two variables. A causal association means there is evidence that alcohol consumption directly causes cancer,” the researcher, Dr. Jennie Connor out of Otago University in New Zealand, explains.
“There is strong evidence that alcohol causes cancer at seven sites in the body and probably others,” she wrote in the study, published Friday in the journal Addiction.
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The more you drink, the more your risk increases, she warns.
“For all these there is a dose-response relationship.” In her piece, she says there isn’t a safe level of drinking either: “a considerable burden is experienced by drinkers with low to moderate consumption.”
The seven cancers tied to booze, according to the paper, are:
- Liver
- Colon
- Rectum
- Breast
- Larynx
- Esophagus
- Oropharynx
She also points to growing evidence that alcohol could cause:
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- Skin
- Prostate
- Pancreatic cancer
Connor’s comments are based on a review of major research and meta-analyses that zeroed in on alcohol and cancer. Some of the research came out of the World Cancer Research Fund, the American Institute for Cancer Research, and the International Agency for Research on Cancer (the IARC already classifies alcohol as ‘carcinogenic to humans).
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Connor says she learned that many of these studies found a link. How strong the ties were depended on the cancer, too: mouth, pharynx and esophagus were most affected.
For these cancers, there is a “well-recognized interaction” of alcohol with smoking, multiplying risk, she explained.
She says, overall, 5.8 per cent of all cancers can be attributed to alcohol.
If consumers quit drinking, the causal association tapers out, which props up their findings, her research says.
Those who give up on booze could even end up with the same risk levels as “never drinkers” after 20 years.
“This raises the question of why alcohol affects some cancers and not others, and whether this undermines the conclusion that ‘alcohol causes cancer,’” she concedes.
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But she says the mechanisms behind why alcohol causes cancer is “not well understood” for now.
The Distilled Spirits Council disagreed with the findings, though.
“To declare that alcohol definitively causes cancer based upon cherry-picked epidemiology articles lacks scientific credibility,” Dr. Sam Zakhari, senior vice president of scientific affairs at the organization, said in a statement.
“Based on my own 40-year career as a biomedical scientist,…the science regarding cancer and alcohol consumption is far from settled. In fact, the existing epidemiological studies do not demonstrate causation, nor do they account for the multitude of contributing factors,” he said.
In 2014, Cancer Care Ontario warned that alcohol is an overlooked risk factor for cancer, just like smoking, tanning or an unhealthy diet.
“Alcohol drinking has been normalized in our society and so much so that we don’t think of it as a risk factor for chronic diseases, especially cancer,” Dr. Linda Rabeneck, CCO’s vice-president of prevention and cancer control, said.
“This is an opportunity to show that it’s a modifiable risk factor and there are people who are diagnosed with cancers that we can relate to alcohol,” she told Global News.
Read Connor’s full paper here.
carmen.chai@globalnews.ca
Follow @Carmen_Chai
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