Alcohol use and cancer, what do we know about their relationship?
Most people know that heavy drinking can cause health problems. But many people might not know that drinking alcohol also can raise their risk of getting cancer.
Cancers linked to alcohol use
Alcohol use has been linked with cancers of the:
- Throat (pharynx)
- Voice box (larynx)
- Colon and rectum
Alcohol may also increase the risk of cancers of the pancreas and stomach.
For each of these cancers, the more alcohol you drink, the higher your cancer risk.
_ 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 even more than drinking or smoking alone. This might be because alcohol can help harmful chemicals in tobacco get inside the cells that line the mouth, throat and esophagus. Alcohol may also limit how these cells can repair damage to their DNA caused by the 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 and scarring. This 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 this is generally stronger in men than in women, but 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 also raise estrogen levels in the body, which may explain some of the increased risk. Cutting back on alcohol may be an important way for many women to lower their risk of breast cancer.
How does alcohol raise cancer risk?
Exactly how 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 by the alcohol may try to repair themselves, which could lead to DNA changes that can be a step toward cancer.
Bacteria that normally live in the colon and rectum 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 may help 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 smoking or drinking alone.
In other cases, alcohol may slow the body’s ability to break down and get rid of some harmful chemicals.
Effect on absorption of folate or other nutrients
Alcohol might affect the body’s ability to absorb some nutrients, such as folate. Folate is a vitamin that cells in the body need to stay healthy. Absorption of nutrients can be even worse in heavy drinkers, who often have low levels of folate. These low levels may play a role in the risk of some cancers, such as breast and colorectal cancer.
Effects on estrogen or other hormones
Alcohol can raise the 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 effects, alcohol may contribute to cancer growth in other, unknown ways.
Other long-term health effects from drinking alcohol
Most people know about the short-term effects of drinking alcohol, such as its effects on mood, concentration, judgment, and coordination. But alcohol can also have longer-term health effects. These can vary from person to person.
For some people, alcohol is addictive. Drinking can become heavier over time, leading to serious health and social problems. Heavy drinkers who suddenly stop drinking can have physical withdrawal symptoms such as tremors, confusion, hallucinations, seizures, and other serious problems over the next few days. In some people these can be life-threatening. This doesn’t mean that heavy drinkers should not stop drinking. It does mean that heavy drinkers should talk with their health care team about the safest way to stop drinking.
Over time, heavy drinking can cause inflammation (hepatitis) and heavy scarring (cirrhosis) in the liver. This can lead to liver failure. Heavy drinking can also damage other organs, such as the pancreas and the brain, and can raise blood pressure. It also increases the risk of heart disease and stroke.
In pregnant women, alcohol use, especially heavy drinking, may lead to birth defects or other problems with the fetus.
On the other hand, low to moderate alcohol use has been linked with a lower risk of heart disease in some people. Low to moderate use is usually defined as 1 or 2 drinks a day for a man or 1 drink a day for a woman. The potential benefit of lowering heart disease risk has to be weighed against the possible health risks for each person.