Should your cocktail carry a cancer warning?

When the pandemic struck last year, many Americans rushed to stock up on alcohol, causing retail sales of wine, beer and liquor to surge across the country.

But the uptick in sales was a worrying sign for health experts focused on cancer prevention. In recent years, a growing number of medical and public health groups have introduced public awareness campaigns warning people to drink with caution, noting that alcohol is the third leading preventable cause of cancer, behind tobacco and obesity.

In October, the American Society for Clinical Oncology (ASCO), which represents many of the nation’s top cancer doctors, along with the American Institute for Cancer Research, the American Public Health Association and five other groups, called on the federal government to add a cancer warning to alcohol labels, saying there was strong scientific consensus that alcohol can cause several types of cancer, including breast and colon cancers. While medical experts have long recognized alcohol as a risk factor for various cancers, including cancers of the mouth, throat, voice box, esophagus and liver, a survey conducted by ASCO in 2017 of 4,016 American adults found that fewer than a third recognized alcohol as a risk factor for cancer.

Other countries are stepping up public health efforts to rein in alcohol consumption as well. The European Union, which has some of the highest levels of drinking in the world, announced earlier this year that it planned to slap new health warnings on alcohol and explore new taxes and restrictions on the marketing of alcoholic beverages as part of a $4.8 billion plan to reduce cancer rates. In France, famous for its wine and sparkling wine, the government announced that it would issue new warnings and policies to discourage heavy drinking as part of a 10-year plan to tackle cancer, which is the country’s leading cause of death.

The ongoing pandemic underscores the urgency of these efforts, as stress, lockdowns and economic uncertainty continue to take a toll. In the past year, hospitals across the United States have reported an increase in admissions for hepatitis, liver failure and other alcohol-related diseases. A study in the journal Psychiatry Research found that in the first six months of lockdowns, alcohol abuse rose most sharply among people who lost their jobs or who were confined to their homes because of shelter-in-place restrictions. The pandemic has also made it easier for people working from home to drink throughout the day without fear of colleagues noticing.

“Workers who would never consider consuming alcohol at the office are now free to drink to excess during work hours while at home,” the study found. “There are grave concerns over the long-term health implications of the rising level of alcohol dependence.”

In the United States, 41 per cent of men and 39 per cent of women will develop cancer at some point in their lifetimes, according to the American Cancer Society. The group estimates that around 42 per cent of newly diagnosed cancers are potentially preventable, by avoiding such measures as cigarette smoking (accounting for some 19 per cent of cancer cases), excess weight (7.8 per cent of cases), drinking alcohol (5.6 per cent of cases), ultraviolet radiation (5 per cent of cases) and physical inactivity (2.9 per cent of cases). While heavy drinking poses the greatest hazard, moderate drinking — generally defined as two drinks a day for men and one drink a day for women — can also imperil health. According to the cancer society, even small amounts of alcohol — less than one drink a day — can raise the risk of breast cancer in women and some other forms of the disease.

The link between alcohol and cancer was the focus of a recent large study that found that alcohol causes 75,000 new cases of cancer in the U.S. every year, as well as 19,000 deaths from the disease. The study, published in January in Cancer Epidemiology, concluded that alcohol accounted for more than one in eight cases of breast cancer in women and one in 10 cases of colorectal and liver cancers nationwide.

“It’s a substantial number of cancer cases and cancer deaths that could be prevented,” said Dr. Farhad Islami, the senior author of the study and the scientific director of the cancer disparity research team at the American Cancer Society. “The cancer burden is considerable.”

Scientists have known that alcohol promotes cancer for several decades. The World Health Organization first classified alcohol consumption as cancer-causing in 1987. Experts say that all types of alcoholic beverages can increase cancer risk because they all contain ethanol, which can cause DNA damage, oxidative stress and cell proliferation. Ethanol is metabolized by the body into another carcinogen, acetaldehyde, and it can influence breast cancer risk by elevating estrogen levels.

But surveys continue to show that most people remain unaware of the risks. When the American Institute for Cancer Research surveyed Americans two years ago to gauge their awareness of different cancer risk factors, the results were striking: Fewer than half were aware of the alcohol-cancer link.

Experts say one reason for the lack of awareness is the popular idea that moderate alcohol intake, especially of red wine, is good for heart health, which has drowned out public health messages about alcohol’s effect on cancer risk. But while moderate drinking has long had a health halo, recent studies suggest it may not be beneficial at all. The American Heart Association states that “no research has established a cause-and-effect link between drinking alcohol and better heart health” and that people who drink red wine may have lower rates of heart disease for other reasons, such as healthier lifestyles, better diets or higher socioeconomic status.

Other analyses have found that moderate drinking can appear to be beneficial in large population studies because the “nondrinkers” who are used for comparison often include people who don’t drink because they have serious health issues or because they are former heavy drinkers. When studies take these factors into account, the apparent cardiovascular benefits of moderate drinking disappear.

For that reason, the federal government’s Dietary Guidelines for Americans, which once promoted moderate drinking for heart health, no longer makes that claim. A panel of scientists that helped shape the most recent edition of the guidelines called for the government to lower the recommended daily limit for alcohol consumption to just one drink a day for both men and women, citing evidence that higher levels of alcohol intake increase the risk of early death.

But the alcohol industry lobbied fiercely against that change, and the latest guidelines, published in December, did not include the lowered drink recommendation. The guidelines, however, did for the first time include strong language about alcohol and cancer, warning that even moderate drinking can “increase the overall risk of death from various causes, such as from several types of cancer and some forms of cardiovascular disease.”

“For some types of cancer,” the new guidelines state, “the risk increases even at low levels of alcohol consumption (less than one drink in a day). Caution, therefore, is recommended.”

The American Cancer Society also issued new guidelines last year that for the first time took a tough stance on drinking, warning that for cancer prevention, “there is no safe level of consumption.” Dr. Timothy Naimi, a member of the government’s dietary guidelines advisory committee, said the new recommendations make clear that moderate drinking is not protective and that drinking less is always better than drinking more.

“The new guidelines are very strong in framing alcohol as a leading preventable health hazard,” said Naimi, director of the Canadian Institute for Substance Use Research. “I think the relationship between alcohol and a number of the most important cancers is still not widely recognized. But I feel that’s changing.”

Nigel Brockton, vice president of research at the American Institute for Cancer Research, said he worried that people who increased their alcohol intake in the past year to cope with the pandemic might continue their new habits into the future. But he advised people who drink to avoid making it a daily habit and to take other steps to lower their risk, such as exercising and improving their diets.

“We’re not expecting everyone to become teetotalers,” he said. “But if you’re going to drink, then one is better than two, and not every day, because those are the behaviors that across all of these cancers increase your risk.”