A study of existing research found strong evidence of a direct, harmful effect of drinking, even though scientists are unsure of the exact biological reasons why alcohol causes cancer.
Writing in the journal Addiction, Jennie Connor, from the University of Otago in New Zealand, said alcohol is estimated to have caused about half a million deaths from cancer in 2012 alone – 5.8 per cent of cancer deaths worldwide.
The highest risks are from heavy drinking, but even people who drink at low levels are at risk. Her review linked alcohol to cancer of the mouth and throat, larynx, oesophagus, liver, colon, bowel and breast.
She said: “There is strong evidence that alcohol causes cancer at seven sites, and probably others.”
Based on current evidence, she said there is no safe level of drinking with respect to cancer though the risks are reduced for some cancers when people stop drinking.
She added that the supposed health benefits of drinking – such as red wine being good for the heart – were “seen increasingly as disingenuous or irrelevant in comparison to the increase in risk of a range of cancers”.
In January, the UK’s chief medical officers said no level of regular drinking is without risks to health.
Publishing recommendations, they said men should consume no more than 14 units of alcohol per week, down from the previous 21 units, bringing them into line with the recommendation for women.
Modelling for the study showed that, compared with non-drinkers, women who regularly drink two units a day have a 16 per cent increased risk of developing breast cancer and dying from it.
Those who regularly consume five units a day have a 40 per cent increased risk.
For every 1,000 women who do not drink, 109 will develop breast cancer. This rises to 126 women for those who drink 14 units or less per week.