The relationship between humans and alcohol stretches back thousands of years and it’s an integral part of many societies’ social lives. However, we are aware that this relationship has never been a healthy one. The WHO European Region has the highest level of alcohol consumption in the world, in part driven by high consumption in the central and eastern parts of the region. Consequently, the alcohol attributable disease burden is also high in this region with diseases such as cirrhosis, pancreatitis, cardiovascular diseases and at least 7 different types of cancer.
Types of cancer caused by alcohol
There are seven types of cancer linked to alcohol – bowel, esophageal, larynx, mouth, pharynx, breast and liver. There’s also evidence that heavy drinking might be linked to pancreatic cancer.
There are many theories on how alcohol causes some types of cancer and not other types. The best evidence we have is for mouth and throat cancers where alcohol directly damage cells in these tissues. And, because alcohol also increases a person’s chances of developing a scarring of the liver known as cirrhosis, it’s thought that this increases their chances of developing liver cancer.There’s also some evidence that certain bacteria in your mouth, throat and bowel could be involved in alcohol causing cancer.
Alcohol increases a woman’s chances of developing breast cancer, but how and why this happens still isn’t fully understood. One theory is that drinking alcohol affects women’s hormone levels, increasing the amount of estrogen in the body, which is then used by breast cancer cells as fuel for growth.
The alcohol breakdown
Like most things you eat or drink, alcohol, be it in a beer, shot or cocktail, gets broken down by your cells.In the case of ethanol, it ultimately gets broken down to create energy.
First an enzyme called alcohol dehydrogenase (ADH) converts ethanol to another molecule – acetaldehyde. This then gets broken down by a second enzyme, acetaldehyde dehydrogenase(ALDH), into acetate, which our cells can use as a source of energy.
Ethanol itself is relatively non-toxic other than the consequences of drunkenness. It doesn’t directly damage DNA. But as the body breaks it down, it goes through a step where it is converted to a highly reactive, toxic chemical called acetaldehyde. And it’s a build-up of this which likely causes changes that lead to cancer.
To prevent acetaldehyde building up and damaging DNA, human cells contain three ALDH enzymes – ALDH1A1, ALDH2 and ALDH1B1, which rapidly break down acetaldehyde into acetate. This means that acetaldehyde doesn’t usually have time to build up or hang around for long enough to cause significant DNA damage. But this protection mechanism can be overwhelmed once alcohol is in the bloodstream, meaning it doesn’t work properly.
What’s more, it isn’t available to everyone. Some people have mistakes or changes in the genetic code of their ALDH enzymes which cause them to malfunction, so acetaldehyde can build up. In turn, this leads to DNA damage.
Thankfully, our cells contain a further layer of protection, in the form of a variety of ‘toolkits’ that can repair damaged DNA. But both of these systems have their limits and if you overwhelm them, acetaldehyde can cause the damage and lead to cancer.
Behind all the mechanisms that cause cancer , one thing is clear.
The best way to reduce the risk of cancer from alcohol is to drink less, whether by having more alcohol-free days every week, by switching from alcohol to soft drinks during a night out, or by picking smaller servings.
We know that adults have the right to decide how much they want to drink, but the impact of alcohol on our health is undeniable. By working with our governments, policy-makers and healthcare professionals, we should raise awareness of the risks of alcohol and help people make informed choices that can reduce their cancer risk.