Alcohol is one of the risk behaviours that scientific evidence confirms to be linked with the development of cancer. The International Agency for Research on Cancer (IARC) classifies alcohol as a Group 1 carcinogen in humans — the same category as major carcinogens such as tobacco and asbestos.

This is consistent with the report of the World Cancer Research Fund and the American Institute for Cancer Research (WCRF/AICR), which states that the relationship between alcohol consumption and cancer is at the Convincing: Increases Risk level — that is, there is strong evidence that it can increase the risk of developing cancer. In addition, the U.S. National Toxicology Program (NTP) concluded as early as the year 2000 that the consumption of alcoholic beverages is a human carcinogen.

At present, alcohol is found to be associated with at least seven types of cancer: oral cavity cancer, pharyngeal cancer, laryngeal cancer, oesophageal cancer, colorectal cancer, liver cancer, and breast cancer. A 2020 report estimated that there were approximately 741,000 new cancer cases worldwide — about 4% of all cancer patients — directly related to alcohol consumption.

How Does Alcohol Contribute to the Development of Cancer?

Empirical biological evidence indicates that ethanol in alcohol can trigger the development of cancer through the following key mechanisms:

• Mechanism 1: When alcohol enters the body, it is broken down by the enzyme Alcohol Dehydrogenase (ADH) into “acetaldehyde” (Acetaldehyde), a toxic substance that can directly damage genetic material (DNA), causing cells to divide abnormally, lose control, and ultimately undergo mutation that leads to cancer.
• Mechanism 2: The metabolism of alcohol generates free radicals (Reactive Oxygen Species: ROS), which stimulate inflammation within the body and cause damage to genetic material, proteins, and lipids through the process of oxidation (Oxidation).
• Mechanism 3: Alcohol can disrupt the body’s hormonal balance, particularly oestrogen, which plays an important role in the growth of breast cancer cells, thereby increasing the risk of this type of cancer.
• Mechanism 4: Alcohol has solvent properties. In people who smoke, carcinogens from cigarette smoke can penetrate the body’s tissues more easily, greatly increasing the risk of oral cavity and pharyngeal cancer.

The More You Drink, the Higher the Cancer Risk

Even drinking alcohol in small amounts may increase the risk of certain types of cancer compared with those who do not drink alcohol at all, and the more one drinks, the higher the risk becomes accordingly.

For example, a study in Australia that followed 226,162 people aged 45 years and over found that among women who drank less than 1 drink per week, the risk of developing cancer was 16.5%; the risk increased to 19.0% with an average of 1 drink per day, and rose to 21.8% with an average of 2 drinks per day.

Meanwhile, among men who drank less than 1 drink per week, the risk was 10.0%; it increased to 11.4% with an average of 1 drink per day, and to 13.1% with an average of 2 drinks per day.

At present, medical evidence clearly indicates that “there is no safe level of alcohol consumption” in terms of cancer prevention. Even drinking in small amounts may increase the risk if accumulated over the long term. Therefore, reducing, cutting down, or avoiding alcohol consumption is an important way to reduce the risk of cancer and promote good health in the long term.

On the occasion of National No-Alcohol Day on 30 July 2026, this is an important opportunity to raise awareness of the cancer risk associated with alcohol consumption and to begin changing behaviours, in order to reduce risk and promote good health in the long term.

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References

• [1] Rumgay H, Shield K, Charvat H, Ferrari P, Sornpaisarn B, Obot I, Islami F, Lemmens VEPP, Rehm J, Soerjomataram I. Global burden of cancer in 2020 attributable to alcohol consumption: a population-based study. Lancet Oncol. 2021 Aug;22(8):1071–80.
• [2] Jemal A, Sung H, Kelly K, Soerjomataram I, Bray F (Eds). The Cancer Atlas. Fourth Ed. Atlanta, GA: American Cancer Society, 2025. Also available at: https://canceratlas.cancer.org/.
• [3] National Cancer Institute. Alcohol and Cancer Risk [Internet]. Maryland: National Cancer Institute, National Institutes of Health; 2025 May 2 [cited 2026 Apr 20]. Available from: https://www.cancer.gov/about-cancer/causes-prevention/risk/alcohol/alcohol-fact-sheet
• [4] Sarich P, Canfell K, Egger S, Banks E, Joshy G, Grogan P, Weber MF. Alcohol consumption, drinking patterns and cancer incidence in an Australian cohort of 226,162 participants aged 45 years and over. Br J Cancer. 2021 Jan;124(2):513–23.