One or two units of alcohol a day can increase the risk of cancer
Posted Apr 09 2009 7:17pm
Alcohol increases the risk of seven types of cancer
From riotous nights in the pub to a quiet glass with dinner, alcohol is an ever-present part of British life. But it has its dark side, leading to hangovers, embarrassment or worse.
After smoking, drinking alcohol is one of the most important and well established causes of cancer – a message that has been clearly backed up by a large new study.
The Million Women Study has just reported that drinking more than two units of alcohol per day can increase the overall risk of developing cancer, as well as boosting the risk of developing seven specific types.
To put things into perspective, two units is the amount in a 175ml glass of wine, or a pint of ordinary strength lager, cider or bitter.
We’ll look into the findings in much more detail in the rest of the post, but its message is clear: the less alcohol you drink, the lower your risk of cancer.
What did the study show?
The Million Women Study includes over 1,280,000 British women. They were recruited between 1996 and 2001 by Cancer Research UK scientists in Oxford, led by professor Valerie Beral.
The study’s latest report looked at how alcohol affects the risk of 21 different types of cancer. According to the results, regularly drinking small amounts of alcohol increases the risk of:
Laryngeal (voicebox) cancer
Oesophageal (gullet or foodpipe) cancer
Pharyngeal (upper throat)cancer
Some of these effects are pretty substantial. Compared to women who drink two units a week, those who drink two per day double their risk of mouth and laryngeal cancer, and triple their risk of developing a certain type of oesophageal cancer.
Other studies have found the same thing, and the link between alcohol and cancer is now very well established.
What about light drinking?
We’re all aware that binge-drinking can have serious consequences for your health, from alcoholism to cirrhosis of the liver.
But studies like this tell us that as far as cancer goes, drinking much less can still be risky. Drinking just 1-2 units a day can increase your risk of the seven cancers linked to alcohol. And the more you drink, the higher that risk becomes.
And remember that a small glass of wine or a pint of regular-strength beer already contains that many units.
But does alcohol have any benefits?
The study also found that alcohol has a protective effect against certain types of cancer. Women who drink more tend to have lower risk of kidney and thyroid cancer, as well as non-Hodgkin lymphoma. It’s not clear why this happens, although other studies have found the same thing.
Even so, there’s no doubt that these potential benefits can’t compensate for the serious consequences of drinking too much. Indeed, the study showed that drinking two units a day, compared to two a week, increases the risk of cancer overall by 15%.
It’s a clear sign that the risks outweigh the benefits.
That’s especially ironic since some media reports suggest that alcohol could actually prevent some of the cancers we know that it causes. Often, these reports are based on very small studies, or look at cancer cells grown in a plastic dish, rather than real people. Either way, it’s clear that following this advice could be harmful and potentially fatal.
What about wine, or red wine in particular?
Although many people believe that wine, and red wine in particular, is generally good for their health, scientific studies say otherwise.
The vast majority have found that all types of alcohol – beer, wine and spirits – can increase the risk of cancer. The Million Women Study is no exception.
It showed that even women who only drank only wine (about a third of the sample) have a higher risk of cancer in a similar way to women who drink beer or spirits too. Both red and white wines had the same effect.
What about smoking?
The study found that alcohol only really increases the risk of mouth, oesophageal and laryngeal cancers in people who also smoke. Among people who had quit smoking or had never started in the first place, the extra risk was minimal.
However, note that smoking doesn’t cause breast cancer, so drinking one or two units a day will increase the risk of this cancer even in women who don’t smoke.
How many cancers are we actually talking about?
If you look at every woman in the UK under the age of 75, the Million Women Study estimates that every extra alcoholic drink per day is responsible for 15 cancers in every 1000 women. Out of those, the majority (11 out of 15) are breast cancers.
All in all, the researchers estimate that every year in the UK, alcohol causes:
5,000 breast cancers (just over one in ten cases)
1,200 mouth, oesophageal or laryngeal cancers (about one in twelve cases)
500 bowel cancers
250 liver cancers
How does alcohol cause cancer?
Alcohol could lead to cancer in several different ways:
In your body, alcohol is converted into a toxic chemical called acetaldehyde, which is one the main reasons why we get hangovers. But besides giving you a headache in the morning, acetaldehyde can also cause cancer by damaging DNA and stopping our cells from repairing this damage.
Alcohol can increase the levels of some hormones, such as oestrogen, testosterone and insulin. Unusually high levels of oestrogen increase the risk of breast cancer.
Alcohol makes it easier for the tissues of the mouth and throat to absorb the cancer-causing chemicals in tobacco. This is one reason why people who smoke and drink multiply the damage they receive and have especially high risks of cancer.
Drinking lots of alcohol can damage the cells of the liver, causing cirrhosis, a disease that makes people more vulnerable to liver cancer.
The bottom line
For many of us, alcohol is a regular and enjoyable part of our lives. But it’s important that we at least realise how our drinking habits can affect our health.
Many people associate alcohol with social problems and when health comes into it, it’s usually associated with heavy binge-drinking.
Unfortunately, it’s clear from studies like this that what most of us would consider as “light” or even “moderate” drinking can affect the risk of several cancers. You don’t need to be drunk to increase your risk.
Cancer Research UK’s recommendation, which is echoed by other charities, is to limit how much you drink to small amounts - one small drink a day for women or two for men. At these levels, any risk would be fairly limited.
And, of course, every bit you can cut down will help to cut your cancer risk.
Updated with Reference:N. E. Allen, V. Beral, D. Casabonne, S. W. Kan, G. K. Reeves, A. Brown, J. Green (2009). Moderate Alcohol Intake and Cancer Incidence in Women JNCI Journal of the National Cancer Institute DOI: 10.1093/jnci/djn514