(I)
China has one of the highest incidences of esophageal cancer in the world, with incidence rates far exceeding those of developed countries in Europe and the United States. According to China Cancer Statistics, in 2015 alone, 480,000 people were newly diagnosed with esophageal cancer in China, and 380,000 people died as a result.
The question is, why exactly is there so much esophageal cancer in China?
Tumors as a whole are “diseases of the elderly,” and most of them are more prevalent in developed countries. But there are only five common tumors that are more prevalent in developing countries, especially in China. These are the famous “Big Five”: liver, stomach, esophageal, cervical, and nasopharyngeal cancers. Studies have found that the high incidence of these five tumors in China is largely due to acquired causes, including lifestyle and environment.
Esophageal cancer is no exception.
It is easy to imagine that cancer in the esophagus, which is a necessary conduit for everyone to eat and drink, must be closely related to eating habits.
One traditional Chinese habit that may significantly increase the risk of esophageal cancer is to “drink while it’s hot”. I remember from a very young age being served a bowl of very hot soup and told to “drink it while it’s hot”.
A growing body of research has found that drinking something too hot can increase the risk of esophageal cancer. A paper published earlier this year in the International Journal of Cancer demonstrates the correlation once again. Many people don’t know that northeastern Iran is also a region with a high incidence of esophageal cancer. Many people there have a habit of drinking very hot tea. Researchers studied more than 50,000 middle-aged and elderly people there and found that those who like to drink hot tea were 90% more likely to get esophageal cancer than those who don’t!
It was because of studies like these that in 2016, for the first time, the World Health Organization defined beverages above 65°C, collectively, as a Class 2A carcinogen.
Note that theoretically any drink above 65°C, whether it’s coffee, tea, or your mom’s soup.
Coffee and tea both contain some beneficial compounds, and some studies even suggest that drinking coffee or tea may protect against cancer. Drink some if you like, but let it cool before you drink it.
What may actually cause cancer is the inside, too hot water!
(Image from Station Cool Helo)
(II)
So why is it that drinking something too hot for a long time may cause cancer?
Because it causes damage and repair to the esophagus.
Just like boiling water on your hands can burn your skin, drinking something too hot can damage the esophageal mucosa and epithelial cells, causing tissue damage. Once tissue is damaged, it needs to be repaired, a process that requires cell division and growth. Each cell division requires the DNA to be copied all over again, a process that is not 100% accurate and will certainly bring about new mutations. These mutations are random and the vast majority of the time are not cancer-causing, with only a small chance of causing mutations in important cancer-causing genes.
But if you eat something hot for a long time, which leads to repeated damage to the esophageal epithelium, repeated repair, repeated cell division, and repeated mutations, then the probability of causing cancer cells is much higher.
(Image from Station Cool Helo)
In addition to genetic mutations, repeated injury may also cause local chronic inflammation. A number of recent studies have found that chronic inflammation also increases the risk of cancer, including lung cancer and colorectal cancer. This is one mechanism by which taking anti-inflammatory drugs such as aspirin may reduce the risk of colorectal cancer.
The esophagus is really quite uncomfortable.
In fact, almost everyone’s esophagus has been ravaged. A recent paper collected esophageal cells from normal people and then went for genetic testing. The results unexpectedly revealed that even people who don’t have esophageal cancer are full of cells that carry genetic mutations. This is almost certainly the result of a decades-long process of “damage-repair-mutation”.
Drinking less hot stuff won’t prevent 100% of the mutations, but it will reduce the risk.
(3)
Despite the half-hearted talk of hot food, it is only a minor contributor to esophageal cancer in China. The pot for the high incidence of esophageal cancer in China cannot be completely thrown on hot food.
The real first and second risks for esophageal cancer in China are the other two things that can enter the esophagus:
Smoking and alcohol!
(Image from Station Cool Helo)
An important testament to this is that about 70% of the nearly 500,000 people who suffer from esophageal cancer in China each year are men.
In Chinese men, 19.2% of esophageal cancers are due to alcohol use and 18.6% are due to smoking, according to a new study published in The Lancet Global Health 2019.
And as I’ve said before specifically, many people in China are far more likely than in Europe and the United States to have physical damage from drinking, including the development of genetic mutations, because of their genetic inability to successfully metabolize acetaldehyde, the primary carcinogen from alcohol, which may be one of the important factors in the particularly high incidence of esophageal cancer in China.
Think about the people around you who have esophageal cancer, are there more men who like to smoke or drink?
In conclusion, the low incidence of esophageal cancer in Europe and the United States suggests that its greatest risk is lifestyle. If everyone pays attention to healthy living, including quitting smoking and drinking less and controlling hot food, the incidence of esophageal cancer in China is certainly expected to drop significantly.
Lastly, if you are unfortunate enough to be affected, don’t panic. We need to trust the science, follow the cutting-edge information, and find the most suitable treatment for ourselves. Science is advancing quickly, and in fact, just last month, it is believed that as more research is done and more comprehensive therapies emerge, more and more patients with esophageal cancer can achieve long-term survival or even clinical cure.