Researchers have found links between some cancers and alcohol consumption, but not others.
The International Agency for Research on Cancer says that drinking alcohol increases the risk of at least seven cancer types and warns that even low levels of drinking increase cancer risk.
While a number of cancers have been previously linked to drinking alcohol, including those of the breast, bowel, oesophagus, liver, mouth, throat and voice box, researchers from the University of Cambridge and the Karolinska Institute in Sweden said most of the evidence gathered on alcohol and its links to cancer is “observational”.
The new study, which looks at a person’s genes and certain risk factors, has now challenged the genetic link between alcohol and breast cancer.
One academic said the finding suggests that alcohol “only increases cancer risk in body parts with direct exposure to alcohol”.
The technique, known as Mendelian randomisation, looks at genetic differences which have been linked to certain attributes – in this instance, genes linked to whether or not people drink more or less alcohol.
Researchers examined genetic data on 1.4 million people taking part in long-term studies in the UK, the US and Finland.
The study, published in the journal BMC Medicine, found an association between genes linked to greater alcohol consumption and some cancer types.
Researchers said this finding indicates that drinking alcohol raises the risk of cancers of the head, neck, oesophagus and bowel.
But for other cancers, the evidence was inconsistent or absent, the University of Cambridge said.
The research team also found, when specifically looking at the UK data set, that genetically predicted alcohol consumption was linked with a 44 per cent increased risk of cancer death overall.
“Our investigation confirms the harmful effect of alcohol consumption on cancer risk, but suggests that alcohol only increases cancer risk in body parts with direct exposure to alcohol,” said Professor Stephen Burgess, a statistician from the Medical Research Council Biostatistics Unit, part of the University of Cambridge, who oversaw the study.
“In particular, we did not see evidence supporting an effect of alcohol consumption on breast cancer risk, contradicting previous research.”
Dr Susanna Larsson, an epidemiologist based at the Karolinska Institute, who led the study analyses, added: “We could not confirm the link between alcohol consumption and breast cancer risk in our genetic study.
“This could mean the true effect is very small, or that previous findings were influenced by other factors, such as hormone use, which are difficult to fully account for in observational studies.”
Dr Siddhartha Kar, a physician-scientist based at the University of Cambridge, said: “While drinking alcohol, particularly binge drinking, is broadly harmful to human health and society, increasing the risks of heart and liver diseases, dementia, suicide and violence, the impact of alcohol on cancer is likely more limited.”
Main symptoms of breast cancer in women
NHS
Symptoms of breast cancer in women may include:
- a lump, or swelling in your breast, chest or armpit
- a change in the skin of your breast, such as dimpling (may look like orange peel) or redness (may be harder to see on black or brown skin)
- a change in size or shape of 1 or both breasts
- nipple discharge (if you are not pregnant or breastfeeding), which may have blood in it
- a change in the shape or look of your nipple, such as it turning inwards (inverted nipple) or a rash on it (may look like eczema)
- pain in your breast or armpit which does not go away – breast pain that comes and goes is usually not a symptom of breast cancer
Commenting on the study, Dr Claire Knight, senior health information manager at Cancer Research UK, said: “There is strong evidence from decades of high-quality research linking alcohol to many types of cancer, including breast cancer.
“Even small amounts of alcohol can damage the cells of your body. So whatever your drinking habits, cutting down on alcohol is good for your health and can lower your risk of cancer.
“But the world around us can make it harder to make healthier changes, and government support is key.
“That’s why clear warning labels on alcohol are important – to raise awareness and prompt people to think about how much they drink.”
Sally Kum, associate director of nursing and health information at Breast Cancer Now, added: “It’s important to remember that breast cancer risk is influenced by many different factors including genetics, lifestyle and environment.
“Many of these factors are out of our control, and we can’t say for certain what caused someone’s breast cancer.
“While this research suggests that alcohol may not directly cause breast cancer, we know from many other studies that there is a link, even if other factors could be at play.
“More research is needed, but we would still recommend limiting alcohol and making other healthy lifestyle choices, as this has many undisputed health benefits.
“Current national guidance states that people should consume no more than 14 units of alcohol a week spread across three days.”
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