Most Americans are unaware that alcohol is a group 1 carcinogen, along with asbestos, radiation, and tobacco.
Much of the reporting on the health risks associated with drinking focuses on acute or extreme outcomes such as alcohol-related liver disease or traffic fatalities — both of which, along with alcohol use, surged during the pandemic.
We tend to hear less about alcohol’s more insidious health effects — namely cancer. According to a recent study, more than 740,000 worldwide cancer cases in 2020 were due to the consumption of alcohol. And while heavy drinking accounted for most, moderate and even light drinking played a role in approximately 100,000 of those cases.
Indeed, alcohol is not a benign substance. Alcohol is classified by the International Agency for Research on Cancer as a group 1 carcinogen, the highest risk group, which also includes asbestos, radiation, and tobacco. And yet, most Americans are unaware. Surveys show that while 93 percent of the public knows about the cancer risks associated with smoking, only 39 percent are aware of the cancer risks associated with drinking.
Everyday Health spoke with Farhad Islami, MD, PhD, senior scientific director of cancer disparity research at the American Cancer Society, for the latest news and what you need to know about the link between alcohol and cancer.
Q: What do we know about alcohol’s impact on cancer risk?
Farhad Islami: We know that alcohol consumption increases the risk of seven cancer types, including cancers of the oral cavity, pharynx, larynx, esophagus, colorectal, liver, and breast. Nationally, about 5 to 6 percent of cancer cases are attributable to alcohol, accounting for more than 87,000 new cancer cases every year in the United States. And while it’s often thought that only heavy drinking poses a threat, we have evidence that moderate and even light drinking can raise cancer risk. For example, moderate drinking is a known risk factor in colorectal cancer, which is on the rise among younger people in the United States. And research has shown that light drinking can raise the risk of breast cancer, which is also on the rise.
Q: Are certain cancers more closely linked with drinking?
FI: Cancers of the oral cavity and pharynx (throat), grouped together, are the cancer types most closely associated with drinking. Data shows that about 41 percent of these cancers are attributable to alcohol consumption. And then 23 percent of laryngeal cancers (voice box), 22 percent of liver cancers, 21 percent of esophageal cancers, 16 percent of female breast cancers, and 13 percent of colorectal cancers can also be attributed to drinking.
It’s important to understand, however, that just because the alcohol-related risk for a certain cancer type is lower doesn’t necessarily mean we see fewer of those cancers. Even though a smaller proportion of breast cancers are due to drinking than are oral cavity–pharynx cancers, at least 39,000 new cases of breast cancer every year — more than any other type of cancer — are due to alcohol consumption, simply because breast cancer is a much more common cancer.
Q: How does alcohol raise cancer risk?
FI: Alcohol contains ethanol, which is a known carcinogen. There are several ways ethanol acts to cause cancer in the body. For example, ethanol can raise estrogen levels, which in turn increases the risk of breast cancer. In the case of most other cancers, a breakdown product of ethanol known as acetaldehyde can damage DNA and then prevent the body from repairing that damage. In general, cancer risk increases with the amount of ethanol consumed. And because all types of alcoholic beverages contain ethanol, all pose a risk.
Q: Does alcohol affect women’s and men’s cancer risk differently?
FI: On average, men drink more alcohol than women. And because cancer risk increases with the amount of alcohol consumed, the rates and numbers of drinking-related cancers are higher in men than in women. For example, approximately 17 percent of colorectal cancer cases in men are due to alcohol compared with about 8 percent in women. There’s also some evidence that even light drinking may raise the risk.
Women, on the other hand, may be more vulnerable to heavy and binge drinking. There’s research suggesting that women who engage in heavy or extreme binge drinking are 2 to 3 times more likely to develop cancer than men who engage in similarly risky drinking.
Q: Are there other factors that affect risk, for example, race or social determinants of health?
FI: We know that the combination of drinking and smoking can raise cancer risk considerably — to levels that are higher than from alcohol or tobacco use alone. This is especially true for cancers of the oral cavity–pharynx, larynx, and esophagus. And we know that people who live in environments with lower social determinants of health as well as certain groups of people, such as Native Americans, tend to have higher rates of smoking as well as smoking and drinking combined. These groups may also have limited access to early cancer detection and treatment, which can adversely affect outlook and survival.
Q: Does the type of alcohol matter when it comes to cancer risk?
FI: As I’ve said, all types of alcohol contain ethanol, which means that all alcoholic beverages pose a cancer risk — whether wine, beer, or hard liquor. It’s often thought that wine and beer, unlike hard liquor, don’t pose a threat or may even be healthy, but that’s not the case.
Some older data suggested that red wine may benefit the heart and that because it contains antioxidants like resveratrol, may protect against cancer. More recent data shows that wine does not seem to be cardioprotective. And while the jury’s out on resveratrol, we recommend staying away because the harms of alcohol outweigh any possible benefits. Even light drinking raises the odds of breast cancer. A recent study found that for every 10 grams of pure alcohol consumed — the amount in a standard 5-ounce glass of wine — the risk for breast cancer goes up by 5 percent in pre-menopausal women and by about 9 percent in post-menopausal women.
Q: What are the most troubling trends we’re seeing?
FI: While men have historically consumed more alcohol than women in the United States, data shows that the drinking gender gap is closing. Over the last several years, we’ve seen that drinking, and especially heavier drinking, is on the rise among women in the United States. Recent data shows that excessive drinking is rising among women in their late twenties and thirties, and that the prevalence of binge drinking has nearly doubled among women in their thirties and forties. We’re also seeing an emerging trend of “high-intensity drinking,” which is defined as drinking at levels at least 2 times as high as those of binge-drinking — that is, 4 drinks for women and 5 for men in a couple of hours. This is all very concerning.
Q: How much alcohol is safe to drink?
FI: Well, there really is no safe level. According to the American Cancer Society Guideline for Diet and Physical Activity for Cancer Prevention, it’s best not to drink alcohol. People who choose to drink should limit their intake to no more than 2 drinks per day for men and 1 drink a day for women. The recommendation is lower for women because of their smaller body size and because their bodies tend to break down alcohol more slowly.
People often ask whether it pays to stop drinking if they’ve been a drinker in the past, and the answer is yes. Cancer risk begins to decline when people stop, and over time, risk may return to the level of nondrinkers for some cancer types. On another positive note, it’s important to remember that alcohol is one of the most important preventable cancer risk factors, along with tobacco use and excess body weight.