A lot of attention was recently aroused by the plans of the Biden administration to put health warning labels on liquor bottles to reflect the risk of cancer arising from the ingestion of alcoholic beverages. Such warning labels already exist in the European Union.
Does alcohol use increase one’s risk of cancer? In 1981, a landmark study was prepared by Sir Richard Doll and Richard Peto of Oxford University on the causes of cancer. This report was requested by the U.S. Congress so that some perspective could be acquired as to the relative contributions of lifestyle versus environmental versus occupational versus innate factors in causing cancer, and thereby how cancer prevention efforts could be directed by the National Cancer Institute and the government. The resulting document, summarized in a paper in the Journal of the National Cancer Institute, did indeed have a profound impact on subsequent directions in cancer prevention efforts.
Chief among their findings was that 30% of cancer deaths were attributable to tobacco while 35% were due to diet. (They were totally unable to specify exactly which factors in diet to blame and acknowledged that this was just a guesstimate.) I won’t go through each and every item on their list but simply point out, since that is the topic of this article, that they ascribed 3% of cancer to alcohol. Multiple others have made efforts to estimate this as well, and have consistently come up with similar estimates in the 3-4% range.
When one considers this figure, the risk is usually attributed to alcohol consumption that is excessive, and we usually recognize the association of alcohol use and squamous cell malignancies of the upper aerodigestive tract (oral cavity, larynx, esophagus) and of primary liver cancer. The former set of cancers is usually observed in concert with heavy tobacco use. Thus, as cigarette smoking has declined in recent years, the impact of heavy alcohol consumption on squamous cell malignancies of the esophagus and head and neck has likewise declined.
As far as alcohol and the liver is concerned, we are again talking about high enough usage to lead to hepatic cirrhosis. Cirrhosis is severe damage to the liver caused by toxins such as alcohol and which results in liver scarring. Whatever the root cause of the cirrhosis—alcohol consumption, viral infections, fatty liver, etc.—the efforts of the liver to regenerate and repair itself appear to be a pre-carcinogenic process that can eventuate in primary liver cancer. But it takes chronic heavy alcohol use to create the circumstances for these pathways to result in cancer.
Thus, most of the cancer risk we attribute to alcohol is for those who are heavy alcohol users. I don’t think we have to avoid the four cups of wine on Passover or even avoid a beer or glass of wine daily. But is there a deleterious effect from that kind of moderate use, defined as less than two drinks per day for men and less than one drink per day for women? Recent studies have suggested that even such modest consumption can raise the risk of breast cancer. The Nurses’ Health Study (NHS) found a 30% increased risk of breast cancer for women who drank 1.5-2 drinks a day. More dramatically, a study known as the Million Women Study, a cohort study conducted in the U.K., found that women who consumed an average of one drink per day had a 12% increased risk of breast cancer. The former study (the NHS study) included younger women who were generally premenopausal, while the Million Women Study recruited women who were over 50 years of age. This effect on breast cancer appears to be due to increased estrogen and androgen levels in women who consume moderate levels of alcohol.
I should also mention that there is at least some evidence to suggest that alcohol use may also be associated with colorectal cancer risk though I do not believe it is as strong or as consistent.
The risk of cancer associated with moderate alcohol drinking, though definite, is small. Thus, if one goes back to the 3% attributable risk we mentioned earlier in this article from Doll and Peto, most of that risk is due to heavy drinkers; only 0.6% out of that 3% is estimated to be due to moderate drinking.
Many continue to suggest that moderate alcohol use is associated with improved overall health, notably improved overall mortality. Actually, more recent studies do not confirm that. However, a very large, well done meta-analysis by investigators from the University of Victoria in Canada, published in 2023 in JAMA Network Open, did demonstrate quite well, in my view, that moderate alcohol consumption (as defined above) as compared to no drinking did not impart a worse mortality rate on the drinkers. Those who had an increased alcohol consumption (greater than two drinks per day on average) did have a definitely worse overall mortality rate.
Thus, the question one is left with is why the Surgeon General is now making alcohol and cancer an issue. There do seem to be bigger fish to fry.
Alfred I. Neugut, MD, PhD, is a medical oncologist and cancer epidemiologist at Columbia University Irving Medical Center/New York Presbyterian and Mailman School of Public Health in New York. Email: [email protected].
This article is for educational purposes only and is not intended to be a substitute for professional medical advice, diagnosis, or treatment, and does not constitute medical or other professional advice. Always seek the advice of your qualified health provider with any questions you may have regarding a medical condition or treatment.
