1 in 25 newly diagnosed cancer cases in the last year may be associated with drinking alcohol, according to a global study published in The Lancet Oncology.
The study calculated that 17,000 cases of cancer in the UK in 2020 could be linked to alcohol consumption.
The authors of the paper are calling for greater public awareness of the link between alcohol and cancers, and increased government interventions to reduce alcohol consumption in worst-affected regions.
Michelle Mitchell, Cancer Research UK’s chief executive, said: “This research demonstrates there’s still lots of work to do to prevent alcohol-related cancers. There’s strong evidence that drinking alcohol can cause 7 types of cancer and the more someone drinks, the greater their risk.”
How does alcohol cause cancer?
Alcohol consumption has been shown to cause damage to DNA by increasing the production of harmful chemicals in the body. It can also affect hormone production, which can contribute to cancer development, and worsen the cancer-causing effects of other substances, such as tobacco.
Overall, drinking alcohol is known to increase the risk of 7 different types of cancer, including breast, mouth and bowel cancer.
The study found that “risky” and heavy drinking were associated with the largest proportion of cancer cases, but even moderate levels of drinking was linked to almost 1 in 7 of all alcohol-associated cases.
“There’s no ‘safe’ level of drinking, but whatever your drinking habits, cutting down can reduce your risk of cancer,” said Mitchell.
How did the study classify the ‘levels’ of drinking?
The different levels of drinking were defined by the daily amount of alcohol consumption per day in grams – these are grams of pure alcohol, not grams of alcoholic drink:
- Moderate drinking: 0.1 to 20 grams of alcohol per day, the equivalent of up to 2 alcoholic drinks.
- Risky drinking: 20 to 60g per day, between 2 and 6 alcoholic drinks.
- Heavy drinking: more than 60g per day, more than 6 alcoholic drinks.
How did the study work out the number of alcohol-related cancer cases?
The researchers calculated the number of alcohol-related cancers by looking at levels of alcohol intake per person per country for 2010, based on figures including tax and sales data. This is because it takes time for alcohol to affect possible cancer development.
This was then combined with estimated new cancer cases in 2020 for the cancer types with the strongest link to alcohol, plus all cancers combined except non-melanoma skin cancer, and the current data around risk of each cancer from alcohol consumption.
Together, this produced an estimate of 4% (741,300) of all new cases of cancer in 2020 being associated with alcohol consumption.
Cancers of the oesophagus (189,700 cases), liver (154,700 cases), and breast (98,300 cases) accounted for the largest number of new cases, followed by bowel cancers and cancers of the mouth and throat.
Men were found to account for 77% (568,700 cases) of alcohol-associated cancer cases, compared with women, who accounted for 23% of cases (172,600).
However, these numbers are likely to be underestimates.
Professor Amy C. Justice, Yale University, notes that estimating the effects of alcohol intake on cancer rates across countries is notoriously difficult.
In a comment piece for The Lancet Oncology, she writes that a quarter of alcohol purchases are not captured by government data, making it difficult to estimate accurate sales figures. “Achieving a solid understanding of the burden of cancer associated with alcohol use, underlying mechanisms, and how best to intervene rely on accurate measures of alcohol exposure,” she said. “Until we address limitations in measurement, we might be underestimating health risks, especially cancer risks, associated with alcohol.”
What needs to be done?
Harriet Rumgay, of the International Agency for Research on Cancer (IARC), France, says that we urgently need to raise awareness about the link between alcohol and cancer risk among both the general public and policy makers.
Whilst public awareness may drive some individuals to drink less, cutting down their own cancer risk, there are strategies governments can put in place to help too.
“Public health strategies, such as reduced alcohol availability, labelling alcohol products with a health warning, and marketing bans could reduce rates of alcohol-driven cancer. Tax and pricing policies that have led to decreased alcohol intake in Europe, including increased excise taxes and minimum unit pricing, could also be implemented in other world regions,” said Rumgay.
“Local context is essential for successful policy around alcohol consumption and will be key to reducing cancer cases linked to drinking.”
Mitchell agrees: “Minimum Unit Pricing for alcohol, introduced in Scotland and Wales, and shortly in Northern Ireland, would be a positive step for England and we urge UK Government to introduce it here.”