Even though it is well established that chronic use of alcohol does increase the risk for all types of cancer, there is no described causal mechanism to explain this relationship.
There are most likely multiple causes associated with this increase in risk.
Since long-term use of alcohol is associated with a number of conditions that can affect the liver, it should also not be a surprise to readers that long-term alcohol use or abuse is also associated with an increased risk for liver cancer. A number of different research studies have explored this relationship. Just a few results are briefly reviewed below:
- In 2002, the World Health Organization (WHO) estimated that alcohol use causes 20-30 percent of all cases of liver cirrhosis and liver cancer worldwide.
- A 2004 meta-analytic study published in the journal Preventive Medicine investigated the risk for alcohol use and 15 separate diseases, including cirrhosis of the liver and liver cancer, and 156 studies were used in the analysis. It was determined that alcohol intake of 25 gm a day was associated with increased risk of developing different types of cancers. This alcohol intake refers to an intake of pure alcohol. Typically, one standard drink (12 ounces of beer, 5 ounces of table wine, or 1.5 shots of 80-proof liquor) contains about 14 gm of pure alcohol. Thus, individuals who regularly have two or more standard drinks a day are increasing the risk of developing liver cancer significantly. The risk of developing liver cancer was increased 1.8 times for the heaviest users of alcohol, and the risk for developing cirrhosis was 27 times higher for the heaviest users of alcohol. The study also hypothesized that different types of liver cancer as a result of alcohol abuse probably occur due to cirrhosis of the liver related to heavy alcohol abuse.
- A large study published in The Lancet in 2012 reported a dose-related relationship of alcohol use and the risk to develop cirrhosis of the liver and a number of different types of liver cancers, with individuals drinking larger quantities of alcohol on a regular basis demonstrating significantly increased risks for these disorders.
- A large 2013 meta-analytic study published in The Journal of Hepatology indicated that liver cancer deaths attributable to alcohol in 2010 numbered 80,600 in Europe and resulted in over 2 million disability adjusted life years (the number of years lost in all individuals with the condition due to ill health, a disability, or early death). Thus, chronic abuse of alcohol leads to a significant burden on health and disability in Europe (and most likely in other industrialized countries) associated with the development of chronic liver disease.
The bottom line here is that every available study indicates that there is a positive relationship (correlation) between alcohol use and the risk for the development of liver cancer.
Here is what the research findings actually mean:
- The correlation or relationship between alcohol abuse and the risk to develop liver cancer is significant and positive. This means that as individuals use more alcohol and/or use it on a regular basis for longer periods of time, the risk for them to develop liver cancer increases. The relationships are based on group data. Individual cases will vary such that some may not develop any liver issues, whereas others may develop them quickly and with smaller amounts of use or over shorter time periods.
- The relationship is real; however, it is uncertain exactly how this relationship works. These types of findings cannot be used to make a claim that abusing alcohol causes liver cancer; however, they can be used to positively claim that individuals who regularly abuse alcohol are increasing the risk (or probability) that they can develop liver cancer. This is not a foregone conclusion such that alcohol abuse automatically leads to liver cancer. Instead, alcohol abuse leads to a greater potential to develop liver cancer.
- Much of the research points to the notion that alcohol-attributable liver cancer most likely is related to the development of cirrhosis of the liver. Animal models testing the relationship between consuming large quantities of alcohol for lengthy periods of time indicates that alcohol does cause cirrhosis of the liver in animals (however, this is not the only cause of cirrhosis of the liver). These types of findings are directly relatable to humans, and it is assumed that one potential cause of cirrhosis of the liver in humans is chronic alcohol abuse.
- Alcohol abuse is neither a necessary nor sufficient condition for the development of cirrhosis of the liver or for the development of liver cancer. A number of individuals develop these conditions without a history of significant alcohol abuse. However, individuals who chronically abuse alcohol are increasing the risk to develop these conditions. A number of other factors contribute to this increased risk, including genetic factors, the use of other drugs such as tobacco, diet, and other lifestyle and health conditions.
Chronic alcohol abuse is associated with an increased risk to develop liver cancer. Chronic alcohol abuse is also associated with an increased risk to develop a number of other forms of cancer as well. The idea that alcohol abuse causes liver cancer is not fully accurate because there are obviously a number of other factors that interact with this increased risk; however, chronic alcohol abuse is a significant risk factor for the development of cirrhosis of the liver and liver cancer in humans.