Drinking alcoholic beverages is linked to an increased risk of certain cancers. Ethanol in alcohol and its metabolite, acetaldehyde, are classified as Group 1 carcinogens by the International Agency for Research on Cancer (IARC), meaning there’s strong evidence they cause cancer in humans. The risk depends on the amount and frequency of alcohol consumption, with heavier drinking (more than 3 drinks per day) showing a clearer association.
Cancers strongly linked to alcohol include:
- Mouth, throat (pharynx, larynx), and esophagus: Alcohol irritates tissues and may act synergistically with smoking.
- Liver: Chronic drinking leads to cirrhosis, which raises the risk of liver cancer.
- Breast: Even moderate drinking (1-2 drinks per day) increases risk, possibly due to hormonal changes.
- Colorectal: Higher risk with heavy drinking, though the mechanism is less clear.
Light drinking (less than 1 drink per day) shows minimal or no consistent link to cancer risk, but no level is deemed completely "safe." Mechanisms include DNA damage from acetaldehyde, oxidative stress, and interference with nutrient absorption (e.g., folate). Genetic factors, like ALDH2 gene variants common in some populations, can amplify risk by slowing acetaldehyde breakdown.
Data from the American Cancer Society (2020) estimates alcohol contributes to about 5.6% of cancer cases in the U.S. Risk varies by individual factors like genetics, smoking, and diet. Cutting down or avoiding alcohol reduces risk, though not immediately for long-term heavy drinkers.