Alcohol use
is one of the most important preventable risk factors for cancer, along with
tobacco use and excess body weight. Alcohol
use accounts for about 6% of all cancers and 4% of all cancer deaths in the
United States. Yet many people don’t
know about the link between alcohol use and cancer.
Alcohol use
has been linked with cancers of the:
· Mouth
· Throat (pharynx)
· Voice Box (larynx)
· Oesophagus
· Liver
· Colon and Rectum
· Breast
Alcohol
probably also increases the risk of cancer of the stomach, and might affect the
risk of some other cancers as well.
For each of these cancers, the more alcohol you drink, the higher your
cancer risk. But for some types of
cancer, most notably breast cancer, consuming even small amounts of alcohol can
increase risk.
Cancers of
the Mouth, Throat, Voice Box and Oesophagus. Alcohol use clearly raises the risk of these
cancers. Drinking and smoking together
raises the risk of these cancers many times 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 oesophagus. 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, which might be why it raises 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: Drinking
even small amounts of alcohol is linked with an increased risk of breast cancer
in women. Alcohol can raise oestrogen
levels in the body, which may explain some of the increased risk. Avoiding or cutting back on alcohol may be an
important way for many women to lower their risk of breast cancer.
Overall, the
amount of alcohol someone drinks 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.
Exactly how
alcohol affects cancer risk isn’t completely understood. In fact, there are likely several different
ways it can raise risk, and this might depend on the type of cancer.
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.
Once in the body, alcohol can be converted into “acetaldehyde”, a
chemical that can damage the DNA inside cells and has been shown to cause
cancer in lab animals.
Drinking alcohol can also lead to oxidative stress in cells,
causing them to create more reactive oxygen species (chemically reactive
molecules that contain oxygen). These
can lead to damage inside the cells that might increase the risk of cancer.
Alcohol, and its by-products, can also damage the liver, leading to
inflammation and scarring (cirrhosis). As
liver cells try to repair the damage, they can end up with mistakes in their
DNA, which could lead to cancer.
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.
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 consume low levels of
folate to begin with. Low folate levels
may play a role in the risk of some cancers, such as breast and colorectal
cancer.
Alcohol can
raise the levels of oestrogen, a hormone important in the growth and
development of breast tissue. This could affect a woman’s risk of breast
cancer.
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.
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 foetus.
Many studies
have found a link between alcohol use and the risk of developing certain
cancers. But it is not clear whether
alcohol use after treatment might increase the risk of these cancers coming
back (recurring). In theory, it’s
possible that alcohol use might raise the risk of recurrence. For example, alcohol can increase the levels
of oestrogens in the body, which might increase the risk for breast cancer
recurrence. But there is no strong
evidence from studies to support (or refute) this.
In people who have already been diagnosed with cancer, alcohol
intake could also affect the risk of developing a new cancer.
There are
some cases during cancer treatment in which alcohol clearly should be avoided. For example, alcohol, even in very small
amounts, can irritate mouth sores caused by some cancer treatments, and can
even make them worse. Alcohol can also
interact with some drugs used during cancer treatment, which might increase the
risk of harmful side effects. It’s
important to talk with your doctor about this if you are being treated for
cancer.
But for people who have completed cancer treatment, the effects of
alcohol on cancer recurrence risk are largely unknown. It’s important to discuss this with your
doctor.
Factors that
can be important include:
· The type of cancer
· Your risk of recurrence
· Your treatment(s)
· Your overall health
· Other possible health effects of drinking
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