Alcohol Use Linked to Thousands of Cancer Cases in Canada in 2020: Study
TORONTO – Researchers at the Center for Addiction and Mental Health say alcohol has been linked to thousands of cancer cases in Canada last year, and even light to moderate drinking poses a risk of developing the disease in the future.
These findings are part of a World Health Organization International Agency for Research on Cancer (IARC) modeling study that was published this week in the journal Lancet Oncology.
The global study estimates the effect of alcohol consumption on cancers around the world, suggesting that 4% of newly diagnosed cases in 2020 may have been associated with alcohol consumption.
In Canada, researchers have said alcohol consumption was linked to 7,000 new cancer cases in 2020, including 24% of breast cancer cases, 20% of colon cancers, 15% of rectal cancers and 13% cancers of the mouth and liver.
The study found that most of these alcohol-related cancer cases around the world were associated with higher drinking patterns, but researchers estimated that light to moderate drinking – about one or two drinks per day – contributed to over 100,000 cases in 2020, or one in Sept.
“People say, ‘Well, everything causes cancer’, but I would like to point out that alcohol is a Class 1 carcinogen defined by IARC,” Study co-author Kevin Shield said Wednesday, scientist at CAMH’s Institute for Mental Health Policy Research.
“This study establishes that it is one of the leading causes of cancer in the world, and with the increase in alcohol consumption (during the COVID-19 pandemic), we will see it increase even more . “
The IARC includes 121 carcinogens on its list of Class 1 carcinogens on its website, including alcohol, tobacco, ultraviolet rays and outdoor air pollution. Alcohol can worsen the carcinogenic effects of other substances such as tobacco, according to the study.
Shield said there are many ways that alcohol consumption can lead to cancer, but the main mechanism is DNA damage.
“It takes a key number of mutations in your DNA to cause cancer. But over time what happens is that damage accumulates,” he said. “So unfortunately (if) you drink today, you drink tomorrow, you drink the next day, every opportunity to drink increases your risk.”
The study estimated that globally, men accounted for 77 percent (568,700 cases) of alcohol-associated cancer cases, compared to 23 percent for women (172,600). Cancers of the esophagus, liver and breast accounted for the largest number of cases.
The study’s modeling was based on alcohol exposure data, including surveys and sales figures, from several countries. The data were combined with estimates of the relative risk of cancer according to the level of consumption.
Shield said the researchers looked at epidemiological studies of large international cohorts – including Canada, Europe, China and Australia – and checked for other factors that can cause cancer like smoking, obesity and sexually transmitted diseases.
“We make sure that statistically we eliminate these factors, so it’s just alcohol,” he said.
The findings led the study’s authors to call for greater public awareness of the association between cancer and alcohol, urging more government interventions to reduce consumption in the worst-affected areas.
Study co-author Jurgen Rehm, senior researcher at CAMH’s Institute for Mental Health Policy Research, said in a press release that the link between light to moderate drinking and cancer is relatively new.
Rehm added that he doesn’t think public policy reflects the degree of cancer risk and he recommended interventions that included higher taxes on alcohol sales, limited availability and marketing, and added cancer risk warnings to beverage labels.
“With alcohol-related cancers, all levels of consumption are associated with some risk,” he said.
CAMH said its clinic has treated around 3,600 patients in the past year for alcohol use disorders, with Shield adding that Canada has seen an increase in consumption, especially during times of lockdown.
While some increases may be temporary due to stress from the pandemic, researchers said it could lead to potentially harmful habits.
“There are people who are very, very at risk of developing cancer now due to the COVID 19 pandemic,” Shield said. “We are likely to see an increase in our cancer rates because of our increase in alcohol consumption.”
This report by The Canadian Press was first published on July 14, 2021.