A SHOT OF RISK

For many people, alcohol is a common part of socializing. Whether a person enjoys adult drinks at a family gathering, an after-work event, or just catching up with friends, alcohol is often a common theme when people get together.

While many are aware of the more well-known risks of alcohol use, such as alcohol abuse disorder or cirrhosis of the liver, its connection with increased cancer risk, even when people are light consumers of alcohol, is less commonly known.

In fact, more than 50% of U.S. adults reported not knowing how wine, beer, and liquor affected cancer risk, according to a recent study. But in reality, alcohol use accounts for about 6% of all cancers and 4% of all cancer deaths in the United States, according to the American Cancer Society.

While it is generally agreed that decreasing alcohol use can lower cancer risk, there can still be a lot to unpack regarding drinking and how it affects the potential for developing cancer. This is especially true given how often conflicting advice has been given about alcohol and health.

While previous studies concluded that some alcohol consumption, especially red wine, may be beneficial for health, it is likely that any benefit provided by alcohol consumption is outweighed by its risks, according to some experts.

“Up until the 1970s, it was not appreciated that alcohol itself was harmful to the liver, and even in the last two decades, some liver disease literature suggested that light to moderate alcohol use was beneficial rather than harmful. Neither are true,” said Kimberly Forde, Chief of the Division of Hepatology and Associate Professor of Medicine at the Lewis Katz School of Medicine at Temple University. “Over the past few years, that recommendation of moderate alcohol potentially being helpful with respect to heart health and other conditions has really fallen out of favor given the risks.”

ALCOHOL AND THE BODY

The accumulation of evidence strongly suggests that alcohol consumption affects cancer risk, with consumption being linked to several specific types of cancer, including head and neck, esophageal, liver, breast, and colorectal cancer. Although the specific way this occurs is not fully understood, researchers have several theories.

Some research has shown that when ethanol, the actual alcohol in alcoholic drinks, is metabolized by the body into acetaldehyde — a chemical and probable human carcinogen — it can damage DNA. It is also believed that alcohol negatively affects how well the body can break down and absorb nutrients like carotenoids and vitamins A, C, D, and E, which have been associated with lowering cancer risk. In addition, some types of cancer may develop as a result of damage caused by diseases that have been exacerbated by alcohol, such as in cases of alcohol-related liver cancer.

“Many people think if they drink too much they might develop cirrhosis. That’s one thing. But I don’t think that there is an appreciation that alcohol can actually result in cancer,” said Forde.

In alcohol-related liver cancer, individuals typically first develop fatty liver, where the liver is enlarged as a result of built-up fat inside the liver cells. This can then develop into hepatitis and eventually cirrhosis, or scarring of the liver, which can possibly lead to liver cancer.

“By the time this develops, you usually have a somewhat moderately to significantly damaged liver. Unlike other cancers, it tends to happen in a damaged organ. Very rarely do you have a normal liver with a large tumor present,” said Minhhuyen Nguyen, Director of Clinical Gastroenterology at Fox Chase Cancer Center.

“We also frequently see a combination of conditions and lifestyle factors. You might have someone with hepatitis C and cirrhosis who drinks often and has diabetes,” she said.

In cases of alcohol-related head and neck cancer, the effects may be more direct. “With head and neck cancers, we’re talking about structures that the alcohol is actually touching. There’s a suggestion that alcohol itself can be a carcinogen, as alcohol is oxidized to alcohol acetaldehyde, which acts as a carcinogen,” said Jessica Bauman, Chief of the Division of Head and Neck Medical Oncology at Fox Chase. Oxidation is the process through which the liver detoxifies and removes alcohol from the blood.

“But there’s also some thought that alcohol has a more local effect and that it can damage some of the cells of the oral mucosa, or the skin within the mouth. When that happens, it can enhance the penetration of other carcinogens, particularly tobacco,” she said.

Bauman said the introduction of these carcinogens can eventually cause cellular DNA damage and problems with DNA repair, ultimately leading to the development of cancer. This is borne out by studies showing that people who use both alcohol and tobacco have much greater risks of developing throat, larynx, esophagus, and oral cavity cancers than people who use either alcohol or tobacco alone.

“It can be hard to get very clear numbers when it comes to alcohol consumption because it’s so prevalent. Additionally, there are often overlapping risk factors, so we rarely can point to just one of them that led to cancer. We generally think that all of them contribute and together create this milieu that can increase cancer risk,” said Dina Ioffe, Assistant Professor in the Division of Gastrointestinal Medical Oncology at Fox Chase.

DRINKING IN PERSPECTIVE

Although there are often multiple factors at play, the National Cancer Institute’s stance is that there is a strong consensus that alcohol consumption can lead to cancer. And studies show that the more alcohol a person drinks, specifically the more they consume regularly over time, the higher the risk of developing an alcohol-associated cancer.

“There have been studies to look at the risks of very light drinkers, light drinkers, and moderate drinkers. A common question that comes up is about how much of a risk there is. There is at least one study that shows the risk of head and neck cancer is much higher in patients who drink four or more drinks a day compared to one or less drinks a day,” said Bauman.

The Centers for Disease Control and Prevention defines an infrequent drinker as someone who consumes one to 11 drinks in a year, while light drinking is classified as three drinks or fewer per week on average. Moderate drinking refers to more than three drinks, but no more than seven drinks per week for women, and more than three drinks but no more than 14 drinks per week for men.

JOE HURLEY

While the type of alcohol does not seem to play as large a role as the amount consumed, what is considered a standard size drink varies depending on the type of alcohol. The National Institute on Alcohol Abuse and Alcoholism defines a standard drink as one that contains roughly 14 grams of alcohol. This amount is present in 12 ounces of regular beer, five ounces of wine, and 1.5 ounces of distilled spirits.

“Ultimately, I think sometimes people think about how much alcohol it takes to pose a risk, and while there’s no set amount, there’s certainly evidence that shows the more you drink and the longer you drink, the higher the risk of cancers,” said Bauman.

METHODS OF PREVENTION

Although head and neck, esophageal, liver, breast, and colorectal cancer are not always related to alcohol consumption, alcohol is the leading changeable risk factor for cancer in the United States alongside tobacco use.

Because many factors can play a role in how cancer develops, in addition to limiting alcohol and avoiding tobacco, physicians recommend eating a healthy diet and maintaining a healthy weight. It is also recommended that individuals avoid risky behaviors such as unprotected sex and sharing needles and get regular medical care, including necessary screenings. Additionally, receiving vaccines for both human papillomavirus (HPV) as well as hepatitis B, leading causes of head and neck cancer and liver cancer respectively, can help protect against viral causes of those cancers.

“Certainly alcohol and tobacco are major risk factors. Interestingly, however, the alcohol- and tobacco-related head and neck cancers have really decreased in recent years and are being overtaken by HPV-related head and neck cancer. This is often seen in patients who are never drinkers and never smokers or light drinkers, light smokers,” said Bauman. “So the best advice aside from limiting alcohol and avoiding tobacco is to be vaccinated for HPV.”

While the American Cancer Institute recommends not drinking at all based on its ties to cancer, the Dietary Guidelines for Americans from the U.S. Department of Agriculture suggests moderate alcohol consumption is acceptable for those who choose to drink.