There is strong scientific evidence of an association between chronic drinking and several types of cancer. The research evidence indicates that the more alcohol a person drinks over time, the higher their risk of cancer.

Researchers have hypothesized multiple ways that alcohol may increase the risk of cancer:

  • Harmful metabolic byproducts. When alcohol is broken down by the body, its ethanol is metabolized into acetaldehyde. Acetaldehyde is a toxic chemical and a probable human carcinogen that can damage both DNA and proteins. Chronic drinking can also promote generation of reactive oxygen species (chemically reactive molecules that contain oxygen), which can damage DNA, proteins, and lipids in the body via a process called oxidation.
  • Malnutrition. Because alcohol impairs the body’s ability to break down and absorb a variety of nutrients, vitamin deficiencies can occur that are associated with elevated cancer risk. These include vitamin A, nutrients in the vitamin B complex (e.g., folate), vitamin C, vitamin D, vitamin E, and carotenoids.
  • Hormonal changes. Chronic drinking can result in increased blood levels of estrogen, a sex hormone linked to elevated breast cancer risk.
  • Contaminants. Alcoholic beverages may can contain a variety of carcinogenic contaminants that are introduced during fermentation and production. Examples include nitrosamines, asbestos fibers, phenols, and hydrocarbons.

Liver cancer

Alcohol consumption is known to be an independent risk factor for, and a primary cause of, liver cancer.

Esophageal cancer

Alcohol consumption is a major risk factor for a particular type of esophageal cancer called esophageal squamous cell carcinoma.

Head and neck cancer

Alcohol consumption is a major risk factor for certain head and neck cancers, particularly cancers of the oral cavity, throat, and larynx. People who consume 3.5 or more drinks of alcohol per day have a 2-3 times greater risk of developing these cancers than non-drinkers.

Colorectal cancer

A meta-analysis of 57 studies showed that people who regularly drank 3.5 or more drinks per day had 1.5 times the risk of developing colorectal cancer as non-drinkers or occasional drinkers.

Breast cancer

Over 100 epidemiological studies have looked at the association between alcohol consumption and the risk of breast cancer in women. These studies have consistently found an elevated risk of breast cancer associated with increased alcohol intake. A meta-analysis of 58,000 women with breast cancer showed that women who drank more than 3 drinks per day had 1.5 times the risk of developing breast cancer as non-drinkers.

References

NIH: Alcohol's Effects on the Body

NIH: Alcohol's Damaging Effects on the Brain

Healthline: The Effects of Alcohol on the Body

National Cancer Institute: Alcohol and Cancer Risk