Most of us enjoy a drink, but it's hard to separate the facts from the scare stories about the health effects. Here we look at the links between alcohol consumption and cancer as they are currently understood, and answer some of the most frequently asked questions.
See also: Women and cancer: symptoms you should never ignore
See also: Men and cancer: symptoms you should never ignore
Which cancers are linked to alcohol?
There are seven sites for cancer in the human body that have been linked to alcohol consumption: The mouth and throat (oropharynx), the larynx, the oesophagus (gullet), the liver, the colon (bowel), the rectum and the female breast.
Does the risk associated with alcohol vary for these?
Yes, more cases of breast, bowel, oesophagus and mouth and throat cancer have been linked to alcohol in the UK than the other forms of the disease in the list.
However that's not the full story, as the link can be weaker for some forms of cancer than others. A high-profile study found that someone who drinks more than 50g of alcohol per day is four to seven times more likely to develop mouth, throat or oesophagus cancer than a non-drinker. However the risk was found to be just 1.5 times more than a non-drinker for colorectal, liver and breast cancer.
If you are confused by breast cancer being in both lists – it's because it is comparitively common in terms of number of cases, yet alcohol is a low risk factor.
So how does alcohol cause cancer?
Alcohol is converted into a toxic chemical called acetaldehyde in the body, and this has been shown to be capable of damaging DNA and rendering the body incapable of repairing that damage.
Acetaldehyde also causes liver cells to grow at a faster rate than normal. As they regenerate, these cells are more likely to develop changes in their genes which could lead to cancer forming.
Alcohol has also been shown to increase the level of oestrogen in the body – and high levels of the hormone have been linked to an increased risk of breast cancer.
Is it worse to drink and smoke?
Of course those who smoke and drink have a higher risk of developing cancer, but what is particularly worrying is that the two habits have been shown to have a compound effect on the body.
Alcohol and tobacco can work together to multiply the risk of cancer. For example, alcohol can damage the mouth and throat and make them more susceptible to the cancer-causing chemicals contained in tobacco smoke.
Is binge drinking worse than regular and moderate alcohol consumption?
The received wisdom is that binge drinking is more damaging to the body than – for example - taking a single glass of wine with dinner each night.
But when it comes to cancer, research appears to indicate that the same increase in risk is found for the same level of alcohol intake – with no difference seen for whether it was consumed gradually or all in one session.
So what can I conclude from all this?
It's important to note that the studies on the subject are observational, and so they demonstrate a correlation of drinking and cancer rather than a cause.
This doesn't in any way discredit the research, but it means than confounding factors such as other lifestyle choices like smoking, diet and the level of physical activity may also play a role in the development of the disease.
One of the biggest indicators of risk for many cancers are the genes you have inherited – so if you have a family history of the disease, you should be vigilant about increasing other potential risk factors. And that means cutting back on the booze.