Most people know that heavy alcohol drinking can cause health problems. But many people might not know that drinking alcohol can raise their cancer risk.
In fact, alcohol use is thought to account for about 3% to 4% of all cancer deaths each year in the United States.
For each of the following cancers, the risk increases with the amount of alcohol consumed.
Cancers of the mouth, throat, voice box, and esophagus: Alcohol use clearly raises the risk of these cancers. Drinking and smoking together raises the risk of these cancers far more than the effects of either drinking or smoking alone.
This might be because alcohol can act as a solvent, helping harmful chemicals in tobacco to get inside the cells that line the digestive tract. Alcohol may also slow down these cells’ ability to repair damage to their DNA caused by chemicals in tobacco.
Liver cancer: Long-term alcohol use has been linked to an increased risk of liver cancer. Regular, heavy alcohol use can damage the liver, leading to inflammation. This, in turn, might raise the risk of liver cancer.
Colon and rectal cancer: Alcohol use has been linked with a higher risk of cancers of the colon and rectum. The evidence for such a link is generally stronger in men than in women, although studies have found the link in both sexes.
Breast cancer: Even a few drinks a week is linked with an increased risk of breast cancer in women. This risk may be especially high in women who do not get enough folate (a B vitamin) in their diet or through supplements.
Alcohol can affect estrogen levels in the body, which may explain some of the increased risk. Drinking less alcohol may be an important way for many women to lower their risk of breast cancer.
Does the type of alcohol matter?
Ethanol is the type of alcohol found in alcoholic drinks, whether they are beers, wines, or liquors (distilled spirits).
These drinks contain different percentages of ethanol, but in general a standard size drink of any type — 12 ounces of beer, 5 ounces of wine, or 1.5 ounces of 80-proof liquor — contains about the same amount of ethanol (about half an ounce). Of course, larger or ‘stronger’ drinks can contain more ethanol than this.
Overall, the amount of alcohol consumed over time, not the type of alcoholic beverage, seems to be the most important factor in raising cancer risk. Most evidence suggests that it is the ethanol that increases the risk, not other things in the drink.
How does alcohol raise cancer risk?
The exact way alcohol affects cancer risk isn’t completely understood. In fact, there might be several different ways it can raise risk, and this might depend on the type of cancer.
Damage to body tissues: Alcohol can act as an irritant, especially in the mouth and throat. Cells that are damaged may try to repair themselves, which could lead to DNA changes in the cells that can be a step toward cancer.
In the colon and rectum, bacteria can convert alcohol into large amounts of acetaldehyde, a chemical that has been shown to cause cancer in lab animals.
Alcohol and its byproducts can also damage the liver, leading to inflammation and scarring. As liver cells try to repair the damage, they can end up with mistakes in their DNA, which could lead to cancer.
Effects on other harmful chemicals: Alcohol can act as a solvent, helping other harmful chemicals, such as those in tobacco smoke, enter the cells lining the upper digestive tract more easily. This might explain why the combination of smoking and drinking is much more likely to cause cancers in the mouth or throat than either smoking or drinking alone. In other cases, alcohol may slow the body’s ability to break down and get rid of some harmful chemicals.
Lower levels of folate or other nutrients: Folate is a vitamin that cells in the body need to stay healthy. Alcohol use can lower the body’s ability to absorb folate from foods.
This problem can be worse in heavy drinkers, who often do not get enough nutrients such as folate in their diet. Low folate levels may play a role in the risk of breast and colorectal cancers.
Effects on estrogen or other hormones: Alcohol can raise body levels of estrogen, a hormone important in the growth and development of breast tissue. This could affect a woman’s risk of breast cancer.
Effects on body weight: Too much alcohol can add extra calories to the diet, which can contribute to weight gain in some people. Being overweight or obese is known to increase the risks of many types of cancer.
Along with these mechanisms, alcohol may contribute to cancer in other, as of yet unknown, ways.
News source: ACS. The content is edited for length and style purposes.
Figure legend: This Knowridge.com image is for illustrative purposes only.