Health Letter, May 2018
By Azza AbuDagga, M.H.A., Ph.D.
It has been almost a 100 years since the 18th amendment of the Constitution, which prohibited the manufacture, transport and sale of alcohol — including beer, wine and liquor — became effective in the U.S. However, this failed amendment was repealed in 1933 because Americans never stopped drinking alcohol following the implementation of this law.
Although drinking alcohol continues to be a major part of the social fabric of American culture, it also is a major public health problem.
The Centers for Disease Control and Prevention estimated that an average of 88,400 Americans died from alcohol-related causes each year from 2006 to 2010, making alcohol consumption one of the leading preventable causes of death in the U.S.
The immediate harms associated with drinking alcohol — such as alcohol poisoning and injuries (including motor vehicle accidents, falls or drownings) — are well-known to many people.
But how many Americans associate alcohol consumption with cancer? Only 30 percent, according to a recent survey commissioned by the American Society of Clinical Oncology (ASCO).
The following is a discussion of the extent of alcohol consumption in the U.S. and the evidence regarding its relationship with cancer.
Survey data from 2009 to 2011 showed that approximately 70 percent of adult Americans reported drinking alcohol during the preceding year. Twenty-seven percent reported binge drinking (having four or more drinks for women and five or more drinks for men on a single occasion) during the last month. These data also showed that 3.5 percent of adult Americans reported having alcohol dependence.
A 2017 Journal of the American Medical Association – Psychiatry study found a substantial increase in alcohol use, high-risk drinking (four or more drinks for women and five or more drinks for men on any day) at least weekly during the preceding 12 months and alcohol use disorders (including alcohol dependence) in the U.S. from 2001-2002 to 2012-2013. This increase was generally consistent across almost all sociodemographic subgroups, especially women, older adults, racial and ethnic minorities and socioeconomically disadvantaged groups. An accompanying commentary to this study concluded that these findings make “a compelling case that the [U.S.] is facing a crisis with alcohol use, one that is currently costly and about to get worse.”
Alcohol’s link to cancer
Western studies exploring the carcinogenic effect of alcohol date back at least to the beginning of the twentieth century.  Since then, numerous studies have linked alcohol consumption to cancer at seven sites: oral cavity (including pharynx), larynx, esophagus, liver, colon, rectum and female breast. 
The International Agency for Research on Cancer, which is the specialized cancer agency of the World Health Organization, has concluded that there is sufficient evidence for the carcinogenicity of alcohol in humans for the aforementioned types of cancer.  The agency also indicated that the scientific evidence shows little indication that this carcinogenic effect varies by the type of alcoholic beverage.
Moreover, a recent comprehensive meta-analysis (analysis of data from multiple studies) of 572 published studies found a dose-response relationship between alcohol consumption and all of the aforementioned seven types of cancer: Cancer risk increased with higher consumption of alcohol.
Additionally, there is increasing evidence that alcohol consumption is associated with additional types of cancer, including pancreas and prostate cancer and melanoma.
Mechanisms for increased cancer risk
Researchers have found that alcohol may increase the risk of cancer in the following ways:
- Ethanol in alcoholic drinks breaks down into acetaldehyde, which is a toxic chemical and a probable human carcinogen. Acetaldehyde can damage DNA (the genetic material that makes up genes) and proteins.
- Alcohol generates chemically reactive molecules that contain oxygen, which can damage DNA, proteins and fats through a process called oxidation.
- Alcohol impairs the body’s ability to break down and absorb a variety of nutrients including nutrients in the vitamin B complex (such as folate) and vitamins A, C, D and E.
- Alcohol increases the blood levels of estrogen, which has been linked to an increased risk of breast cancer.
Alcoholic beverages also may contain a variety of carcinogenic contaminants that are introduced during fermentation and production, such as nitrosamines, asbestos fibers, phenols and hydrocarbons.
Even low drinking levels can be harmful
Research studies generally show that the greatest cancer risk occurs among heavy and moderate drinkers. Therefore, most recommendations, such as those from the dietary guidelines for Americans, recommend that if alcohol is consumed, it should be done in moderation — up to one drink per day for women and up to two drinks per day for men — for adults of legal drinking age.
Importantly, these guidelines do not recommend that individuals who do not drink alcohol start drinking for any reason.
There is evidence, however, that cancer risk may persist even at low levels of alcohol consumption. For example, a meta-analysis of 222 studies that assessed the association between cancer risk and consumption of one drink or less per day found that even this “light” drinking level is associated with elevated risk of cancer of the oral cavity and pharynx, esophagus and female breast. However, this analysis did not find similar discernable associations with colorectal cancer or tumors of the larynx or liver.
Harms outweigh benefits
A study published on April 14, 2018, in the Lancet examined data on drinking patterns and health outcomes among nearly 600,000 individuals from 19 high-income countries. The study, which examined follow-up data for current drinkers who did not have a baseline history of cardiovascular disease, supported the aforementioned association between alcohol consumption and cancers of the digestive system.
Contrary to the common claims that alcohol drinking may have some cardiovascular benefits, the study showed that alcohol consumption was associated with higher risks of all types of stroke, coronary heart disease excluding heart attack (particularly non-fatal heart attack), heart failure and several less common cardiovascular diseases. Furthermore, the study showed that for cardiovascular diseases other than heart attack, there were no clear risk thresholds below which lower alcohol consumption stopped being associated with lower disease risk.
Importantly, the study showed a steady decrease in life expectancy with increasing alcohol consumption levels. Specifically, individuals who reported consuming more than seven to less than 14 alcoholic drinks per week had an approximately 6-month lower life expectancy at age 40 than did those who reported consuming seven drinks or less per week. Furthermore, individuals who reported consuming more than 14 to less than 25 alcoholic drinks per week had approximately a one-to-two year lower life expectancy at the age of 40 than those who reported consuming seven drinks or less per week. The study estimated that about 20 percent of the alcohol-related survival difference for men (and slightly less for women) was attributed to excess death from cardiovascular disease.
In conclusion, the findings of this study lend support for public policies that call for reducing alcohol consumption limits, particularly for men, in the current U.S. guidelines.
Public health strategies to curb the problem
The following recommendations have been proposed by ASCO to reduce the risks associated with alcohol consumption:
- Health care professionals can screen adults, including pregnant women, for excessive alcohol use to identify people whose levels or patterns of alcohol use place them at increased risk of alcohol-related harms. Health care professionals can then recommend or offer treatment services to those at risk.
- Regulation can be used to reduce the number of sites where alcohol may be legally sold to an individual to either consume on premises, such as in bars or restaurants, or off premises, such as in liquor stores or retail settings.
- The prices and taxes of alcohol can be increased to deter alcohol consumption.
- Limits can be imposed on the days and hours for selling alcoholic beverages in places where alcohol is consumed off premises.
- Laws can be enhanced in all states to better enforce the prohibition on selling alcohol to minors younger than 21.
- Youth exposure to alcoholic-beverage advertisements can be restricted. Early-onset drinking is associated with an increased likelihood of developing a dependence on alcohol later in life. Studies also show that increased advertisements targeted to youth are associated with increased drinking levels.
- Alcohol control strategies can be included in comprehensive cancer control plans at the state, tribal and territorial levels.
- Pinkwashing — the use of the color pink to show a commitment to finding a cure for breast cancer — needs to be eliminated from the marketing of alcohol beverages given their link to the disease.
 International Agency for Research on Cancer (IARC). Consumption of alcoholic beverages. In: Personal Habits and Indoor Combustions. A Review of Human Carcinogens. Vol 100 E. Lyon, France; 2012:373-499.