A global study, published in The Lancet Oncology, suggests that 4% of all newly diagnosed cancers in 2020 may be associated with drinking alcohol, with men accounting for more than three quarters of these cases.
The study estimates that men accounted for 77% (568,700) of 740,000 new alcohol-associated cancer cases, with cancers of the oesophagus, liver, and breast accounting for the largest number of these cases.
Methodology: estimating the number of alcohol-associated cancers in each country
The researchers established levels of alcohol intake per person per country for 2010 (ten years prior to the cancer case data, to allow for the time it takes for alcohol intake to affect possible cancer development) and then combined them with estimated new cancer cases in 2020 (for the cancer types with the strongest evidence of a causal link to alcohol in their main analyses, plus all cancers combined except non-melanoma skin cancer) to estimate the number of alcohol-associated cancers in each country.
To estimate how much alcohol people drank per day, the researchers used estimates for alcohol intake (in litres of alcohol per year per adult) based on alcohol production data, tax and sales data, surveys and opinion on unrecorded alcohol intake, and tourist alcohol consumption data.
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 20g 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, the authors used figures outlining the risk of that cancer from alcohol consumption (per 10 grams of alcohol consumed per day) from existing scientific reports.
Findings: moderate drinking accounted for 14% of the alcohol-caused cancer cases
Globally, an estimated 4% (741,300) of all new cases of cancer in 2020 were 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 colorectal cancers and cancers of the mouth and throat.
Risky drinking and heavy drinking led to the largest proportion of cancer cases at 39% (291,800 cases) and 47% (346,400 cases) respectively. However, moderate drinking was also found to be problematic, with estimates that this level of drinking accounted for 14% (103,100 cases) of the total of alcohol-caused 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
At a country level, the proportions of cancer cases associated with alcohol were estimated to be highest in Mongolia (10%, 560 cases) and lowest in Kuwait (estimated at 0%, less than 5 cases). 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 cases), India at 5% (62,100), China 6% (282,300), Germany 4% (21,500 cases) and France at 5% (20,000 cases – see Appendix table 4 for country level data).
Amongst women, the largest proportions of cancer cases that were attributed to alcohol were estimated to be in the regions of Central and Eastern Europe (3%, 21,500 cases), and Australia and New Zealand (3%, 2,600 cases). Amongst men, the largest proportions of cancer cases linked to alcohol were found in Eastern Asia (9%, 275,900 cases) and Central and Eastern Europe (8%, 49,900 cases).
Limitations: the effects of the Covid-19 pandemic
There are several limitations to the study, including the potential effect of the Covid-19 pandemic, which has impacted behaviours including alcohol drinking and also cancer services in many countries and could therefore have affected cancer risks and diagnosis rates.
Further, the main study analysis did not take into account former drinking, or any relationships between tobacco or obesity with alcohol, which could have attributed some cases to alcohol that were actually driven by, for example, smoking.
The authors also note that in some cases, including Mongolia, they may have over-estimated liver cancers that could have been caused by alcohol because of a possible interaction with Hepatitis B and C virus infection. Further, cancer case records may be of limited quality, especially for low and middle-income countries.
Professor Amy C. Justice, Yale University, USA, (who was not involved in the study), notes that estimating the effects of alcohol intake on cancer rates across countries is notoriously difficult. She writes that a quarter of alcohol purchases are not captured by government data, making it difficult to estimate accurate sales figures. She said “…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… Until we address limitations in measurement, we might be underestimating health risks, especially cancer risks, associated with alcohol.”
The study's authors are calling for greater public awareness of the link between alcohol and cancers
As a result of the study's findings, the lead authors 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.
Ms Harriet Rumgay of the International Agency for Research on Cancer (IARC), said: “We urgently need to raise awareness about the link between alcohol consumption and cancer risk among policy makers 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.”