Cancer biologist reveals how just one alcoholic drink increases your risk of disease
Even the occasional cocktail or glass of wine can be harmful to your health, raising your risk of multiple diseases, including cancer.
Whether consumed regularly or only on special occasions, alcohol takes a toll on your body. From your brain and heart, to your lungs and immune systems, the substance has broad harmful effects – including increasing your risk of cancer.
A 2025 report from the US Surgeon General estimates alcohol is the third-leading preventable cause of cancer in the US and is responsible for about 100,000 cases and 20,000 deaths annually.
Researchers have suspected alcohol could cause cancer for decades and studies have shown it is causally linked to cancer of the mouth, throat, voice box, esophagus, liver, pancreas, stomach, colon and rectum and breast.
In 2000, the US National Toxicology Program concluded consuming alcoholic beverages is a known human carcinogen and about a decade later, the World Health Organization classified alcohol a Group 1 carcinogen, the highest classification, indicating there is enough evidence to conclude a substance causes cancer in people.
Both the CDC and the NIH also agree there is enough conclusive evidence that alcohol causes several types of cancer and US dietary guidelines state even low amounts of alcohol – less than a single drink a day – increase cancer risk.
Despite this, many Americans are not aware that alcohol causes cancer and just 45 percent of US adults are aware alcohol consumption increases risk of cancer, compared to 89 percent of people who know tobacco increases risk.
There are several ways alcohol is thought to encourage cancer, including by producing toxic byproducts in the body and damaging DNA, and as more is revealed about the link, experts are increasingly calling for tighter alcohol consumption regulations.
Women should limit their alcohol intake to no more than one drink per day and men to no more than two drinks per day
According to the 2020-2025 Dietary Guidelines for Americans, women should limit their alcohol intake to no more than one drink per day and men to no more than two drinks per day.
However, those guidelines could change as two researchers who contributed to Canada’s controversial two-drink per week recommendation were said to be advising the US on its new alcohol policies set to be unveiled later this year.
The 2023 National Survey on Drug Use and Health found that over 224 million Americans ages 12 and older drank alcohol at some point in their lifetime – over 79 percent of people in this age group.
I am a researcher studying the biological effects of moderate and long-term alcohol consumption. My team is working to uncover some of the mechanisms behind how alcohol increases cancer risk, including damage to immune cells and the liver.
How does alcohol cause cancer?
Cancer occurs when cells grow uncontrollably in the body. Alcohol may lead to tumor formation by damaging DNA, causing mutations that disrupt normal cell division and growth.
Researchers have identified several mechanisms associated with alcohol and cancer development.
The surgeon general report highlights four ways alcohol can cause cancer: alcohol metabolism, oxidative stress and inflammation, alterations in hormone levels, and interactions with other carcinogens such as tobacco.
Alcohol metabolism is the process by which the body breaks down and eliminates alcohol.
When alcohol breaks down, its first byproduct is acetaldehyde, a chemical that is itself classified as a carcinogen.
Researchers have found certain genetic mutations can lead the body to break down alcohol faster, resulting in increased levels of acetaldehyde.
There is also considerable evidence that alcohol can trigger the body to release harmful molecules called free radicals that are associated with cell damage.
They damage DNA in a process called oxidative stress.
My lab has found that free radicals formed from alcohol consumption can directly affect how well cells make and break down proteins, resulting in abnormal proteins that promote inflammation and favors tumor formation.
Alcohol can also affect hormone levels in ways that increase cancer risk. Moderate alcohol drinking can elevate estrogen levels, which can increase breast cancer risk.
The substance also amplifies breast cancer risk by reducing levels of vitamin A, a compound that regulates estrogen.
Additionally, people who both drink and smoke have an elevated risk of developing cancer of the mouth, pharynx and larynx.
Smoking by itself can cause inflammation and induce free radicals that damage DNA, and alcohol makes it easier for the body to absorb the carcinogens in cigarettes and vapes.
How much alcohol is safe?
You may be wondering how much alcohol you can safely drink and avoid harm. If you ask clinicians and scientists, you might not like the answer: none.
The CDC and American dietary guidelines recommend consuming no more than one drink a day for women and no more than two drinks for men.
The National Institute for Alcohol Abuse and Alcoholism and the surgeon general’s recent advisory have similar recommendations to limit alcohol consumption.
Alcohol consumption is a highly preventable cause of cancer. However, there isn’t currently a way to determine someone’s personal cancer risk from alcohol.
Each person’s individual genetic background, lifestyle, diet and other health factors can all influence the effects of alcohol on tumor formation.
Nevertheless, rethinking your alcohol drinking habits can help protect your health and reduce your cancer risk.
This article is adapted from The Conversation, a nonprofit news organization dedicated to sharing the knowledge of experts. It was written by Pranoti Mandrekar, a Professor of Medicine at UMass Chan Medical School.
