Health Letter, January 2022
By Michael T. Abrams, M.P.H., Ph.D.
There’s no cure, there’s no answer…
Don’t touch that dial
Don’t try to smile…
No booze or
(Jackson J, Night and Day Album, 1982)
Of course, everything is not a carcinogen, but the above lyrics from Joe Jackson do identify two important cancer-causing agents at the close of his satirical refrain; tobacco products and alcohol are both leading causes of cancer. The connection between lung cancer and tobacco is well known, but the carcinogenicity of alcohol is currently more obscure. Accordingly, below is a description of a comprehensive, population-based study published in the August issue of the journal Lancet Oncology that uses a rich collection of epidemiologic data to quantify the link between alcohol consumption and several specific cancers.
Much prior research and analysis has strongly and causally linked the consumption of alcoholic beverages to cancers of the oral cavity, larynx, esophagus, colon, rectum, liver and breast. Worldwide in 2020, per Global Cancer Observatory data from the World Health Organization, there were a total of 6.3 million cases and 3.3 million deaths from these specific cancers.
The recent JAMA Oncology study updated global estimates of “alcohol attributable cancer burden” using cancer incidence data from 2020, alcohol consumption figures from multiple international sources and cancer relative-risk estimates from the scientific literature. This cancer burden was further reported for various drinking levels (moderate, risky, heavy), separately for males and females, and by various geographic regions.
The JAMA Oncology study authors calculated that, worldwide, there were approximately 741,300 new alcohol-attributable cancer cases in 2020 corresponding to 4.1% of all such cases in that year and 8.4 cases per 100,000 persons. Most of the cancer-attributable cases occurred in males (568,700; 77%), and nearly half of all cases occurred in the esophagus (189,700; 26%) or liver (154,700; 21%).
Age-standardized incidence rates of alcohol-attributable cancers showed that many central and eastern European countries (including Moldova, Slovakia and Romania) had the highest incidence rates in males at 23 per 100,000, with the next highest in eastern Asia (including Mongolia and China) at 22 per 100,000, followed by Australia, New Zealand and western Europe at 17 per 100,000. In North America, the incidence rate in males was 13 per 100,000.
The estimated 741,300 cases of alcohol-attributable cancers were divided into the following subgroups by drinking level: 103,100 (14%) were moderate drinkers (consuming up to 20 grams of alcohol per day, the approximate equivalent of two alcoholic drinks per day), 291,800 (39%) were risky drinkers (20-60 grams per day) and 346,400 (47%) were heavy drinkers (over 60 grams per day). Though these results suggest that increasing levels of alcohol consumption correlate with increasing rates of cancer, further stratification of the data revealed that approximately 41,300 new cancers around the globe in 2020 were attributable to drinking up to just 10 grams of alcohol per day (less than or equal to one drink per day).
The JAMA Oncology study authors described several mechanisms for how alcohol leads to cancer, including DNA and other biomolecular damage caused by acetaldehyde (a metabolite of ethanol, the intoxicant in alcoholic beverages), oxidative stress, alterations in the regulation of hormones, and heightening the carcinogenicity of other chemicals like those found in tobacco. Genetic variation also can influence the toxicity of alcohol, as is the case with variations in the aldehyde dehydrogenase gene. In 28–45% of the eastern Asian population, this gene is expressed in a form that yields slower acetaldehyde degradation, which, in turn, may contribute to higher rates of alcohol-attributable cancer.
Other geographic variation is plausibly tied to cultural factors. For example, Saudi Arabia and Kuwait, both nations where alcohol drinking is restricted by Islam-based policies, have some of the lowest alcohol-consumption rates in the world and, correspondingly, they also have low alcohol-attributable cancer rates.
Markedly lower rates of alcohol-attributable cancers in women across the globe also are connected to cultural norms. In reflecting about this prominent finding (recall that men in 2020 were burdened with 77% of all alcohol-attributable cancers), the JAMA Oncology study authors expressed concern that as more women enter paid employment, they are increasing their alcohol consumption and corresponding cancer risk.
The JAMA Oncology authors stated that their cancer incidence estimates are likely conservative because not all cancers were included in the calculations, only those that have thus far demonstrated a sufficient causal link to alcohol. On the other hand, the authors also acknowledge that some of the alcohol-attributable cancers they tallied represent overcounts because of cancer-causing synergies alcohol may have with tobacco, hepatitis or other risk factors.
Finally, the JAMA Oncology study authors noted that the impact of COVID-19 on alcohol use and cancer detection may be a confounding factor eclipsing the true cancer rates detected in 2020. To support that concern, they cited a report from the Netherlands that found that cancer diagnoses dropped by 27% early during the pandemic, recovering only partially through early April 2020. Additionally, they cited a study from the U.K. that reported binge drinking (6+ drinks in a single sitting on a weekly basis) increased during lockdowns. Accordingly, following directly from these two studies, it is plausible that there will be future waves of alcohol-attributable cancers several years from now related to current excessive alcohol use and in the next year or two related to delayed cancer detection.
The JAMA Oncology authors concluded their publication by calling for warning labels on alcoholic beverage containers as one of several public health strategies to increase awareness of the link between such drinks and cancer and to correspondingly mitigate that threat by reducing individual and overall alcohol consumption. Such public health messaging should clearly state that even one drink per day or less increases cancer risk and that alcohol use at increasing levels is strongly associated with other negative and preventable outcomes including accidents, interpersonal violence and dependence.
 GBD 2016 Alcohol Collaborators. Alcohol use and burden for 195 countries and territories, 1990-2016: a systematic analysis for the Global Burden of Disease Study 2016. Lancet. 2018 Sep 22;392(10152):1015-1035.