Alcohol and cancer: which cancers, how much, and what stopping does

Does alcohol cause cancer?

Yes. The NCI says there is strong scientific evidence that drinking alcohol can cause cancer. The International Agency for Research on Cancer (IARC) classified alcohol as a Group 1 carcinogen in 1987, its highest-risk group, which also includes asbestos, radiation and tobacco.

The WHO says alcohol causes at least seven types of cancer, including the most common ones, such as bowel cancer and female breast cancer. It stresses that it is the alcohol itself that causes harm, not the beverage: any drink containing alcohol, whatever its price and quality, poses a risk.

In the US, the NCI says alcohol was responsible for about 5% of the 1.8 million cancer cases diagnosed in 2019, nearly 100,000 cases, and about 4% of cancer deaths that year.

Which cancers are linked to drinking

The NCI lists how much more likely some cancers are in people who drink compared with people who do not. These are relative risks: for a rare cancer, even a large relative increase can mean a small change in someone's actual chance of getting it, while for a common cancer such as breast cancer, a small relative increase can mean many more cases.

How much drinking raises the risk

The NCI says the more someone drinks, the higher the risk, and that even light drinkers can be at increased risk of some cancers. For example, women who have just one drink a day have a higher risk of breast cancer than women who have less than one drink a week.

The NCI also gives absolute numbers from the US Surgeon General's Advisory, using Australian data recalculated in US standard drinks (14 g of alcohol each):

• Women: about 17 in 100 who have less than one drink a week develop an alcohol-related cancer, 19 in 100 at one drink a day and about 22 in 100 at two drinks a day.
• Men: 10 in 100 at less than one drink a week, 11 in 100 at one drink a day and 13 in 100 at two drinks a day.

Is there a safe amount?

The WHO's 2023 statement says there is no safe amount of alcohol that does not affect health. It explains that current evidence cannot show a threshold at which alcohol's cancer-causing effects "switch on", and that around half of the alcohol-attributable cancers in the WHO European Region occur in people whose drinking does not meet the definition of heavy drinking.

The NHS takes the same line in plainer words: it calls drinking under 14 units a week "low risk" rather than "safe", because there is no safe drinking level, and says that drinking more than 14 units a week over many years can increase the risk of mouth, throat and breast cancer. Our page on whether a glass of wine a day is bad applies this to the most common daily habit.

How alcohol may cause cancer

The NCI describes several ways researchers think alcohol raises cancer risk:

• The body breaks alcohol down into acetaldehyde, a toxic chemical and probable human carcinogen that can damage DNA and proteins.
• It generates reactive oxygen species, molecules that can damage DNA, proteins and fats.
• It impairs the absorption of nutrients such as folate and vitamins A, C, D and E.
• It makes it easier for the mouth and throat to absorb harmful chemicals, such as those in cigarette smoke.
• It raises blood levels of oestrogen, which at high levels can cause breast cancer.

Alcohol, smoking and genes

Drinking and smoking together is worse than either alone. The NCI says people who use both have much greater risks of cancers of the mouth, throat, voice box and oesophagus, and that for mouth and throat cancers the harms multiply rather than simply add up.

Genes play a part too. Some people, particularly of East Asian descent, have a form of the enzyme ALDH2 that lets acetaldehyde build up, causing facial flushing and palpitations when they drink. The NCI says people with this variant who drink even moderate amounts have a higher risk of oesophageal and head and neck cancers than people with the usual enzyme who drink the same amount.

What happens to cancer risk when you stop

The NCI says studies have found that stopping drinking is associated with lower risks of mouth and oesophageal cancers, and possibly of throat, breast and bowel cancers. It may take years for the risk to fall to that of people who never drank, but the NCI says it is never too late to stop drinking and reduce the risks.

If you drink heavily, talk to a doctor before stopping: the NHS says stopping suddenly can be very dangerous if you are dependent on alcohol. Our guide on how to cut down on alcohol covers gradual change.

Common questions

When to get help

This site offers self-help tools and information, not medical advice. Talk to a doctor, or call one of the lines below, if:

• you feel shaky, sweaty, sick or anxious when you haven't had a drink;
• you find it hard to stop once you start, or you want to cut down and can't;
• drinking is causing problems with your health, work or the people close to you.

Before you stop: It can be very dangerous to stop drinking suddenly if you are dependent on alcohol. If you get withdrawal symptoms, get medical help before you try to stop drinking.

Sources

1. Alcohol and Cancer Risk. National Cancer Institute. cancer.gov
2. No level of alcohol consumption is safe for our health. World Health Organization, Regional Office for Europe. who.int
3. The risks of drinking too much. NHS. nhs.uk
4. Alcohol-use disorder. NHS. nhs.uk