Researchers are urging the public to learn more about the link between alcohol and cancer after thousands of causal links were reported last year.

The global study found that up to four per cent of newly diagnosed cancer cases in 2020 may have been associated with drinking alcohol.

As well as raising public awareness, researchers are also called for increased government interventions to reduce alcohol consumption in the worst-affected regions.

Men accounted for 77% (568,700) of alcohol-associated cancer cases, compared with women, who accounted for 23% of cases (172,600), the study estimates.

Cancers of the oesophagus, liver and breast made up the largest number of cases.

Harriet Rumgay, of the International Agency for Research on Cancer (IARC), France, said: “We urgently need to raise awareness about the link between alcohol consumption and cancer risk among policymakers and the general public.

“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.

“Local context is essential for successful policy around alcohol consumption and will be key to reducing cancer cases linked to drinking.”

In 2020 there were more than 6.3 million cases of mouth, pharynx, voice box (larynx), oesophageal, colon, rectum, liver and breast cancer, the study estimates based on data from previous years.

The researchers say these cancers have well-established causal links to alcohol consumption, and the estimates of the direct associations with alcohol in the new study are the first of their kind for 2020.

But the disruption to healthcare services across the world due to the coronavirus pandemic are likely to have impacted diagnosis rates for the year and may have led to an underestimation of new cancer cases in the recorded data.

However, this would not be reflected in the study as estimates for 2020 were based on recorded data from previous years.

Alcohol consumption can cause DNA damage through increased production of harmful chemicals in the body, and affect hormone production, which can contribute to cancer development.

Alcohol can also worsen the cancer-causing effects of other substances, such as tobacco.

Researchers established levels of alcohol intake per person per country for 2010 – to allow for the time it takes for alcohol intake to affect possible cancer development, they combined them with estimated new cancer cases in 2020 to estimate the number of alcohol-associated cancers in each country.

They used estimates for alcohol intake based on alcohol production data, tax and sales data, surveys and opinion on unrecorded alcohol intake, and tourist alcohol consumption data to indicate how much alcohol people drank per day.

Moderate drinking was classed as intake of 0.1 to 20 grams per day, the equivalent of up to two alcoholic drinks, risky drinking as 20 to 60g per day, between two and six alcoholic drinks per day, and heavy drinking as more than 60g per day, more than six alcoholic drinks per day.

To estimate the effect of alcohol consumption on each cancer type included, researchers used data outlining the risk of that cancer from alcohol consumption (per 10 grams of alcohol consumed per day) from existing scientific reports.

Globally, an estimated 4% (741,300) of all new cases of cancer in 2020 were associated with alcohol consumption.

Risky drinking and heavy drinking led to the largest proportion of cancer cases at 39% (291,800 cases) and 47% (346,400 cases) respectively, the study found.

However, moderate drinking was an issue, with estimates that this level of drinking accounted for 14% (103,100 cases) of the total of alcohol-linked cases.

Eastern Asia and Central and Eastern Europe regions had the highest proportions of cancer cases that could be associated with alcohol at 6%, with the lowest proportions found in Northern Africa and Western Asia, both below 1%.

The UK had an estimated 4% of cancer cases linked to alcohol (16,800), with the United States at 3% (52,700), Brazil at 4% (20,500), India at 5% (62,100), China at 6% (282,300), Germany at 4% (21,500) and France at 5% (20,000 cases).

There are several limitations to the study, including the potential effect of the Covid-19 pandemic and that the main study analysis did not take into account former drinking, or any relationships between tobacco or obesity with alcohol.

The study is published in The Lancet Oncology.