Why is 40% of the world's esophageal cancer cases in China?

Chinese people always say that "food is the primary need of the people". Eating is of such great significance, but the prevalence of digestive diseases and tumors among Chinese people is relatively high, among which esophageal cancer is the most typical.

More than 40% of esophageal cancer patients in the world are Chinese. For gluttonous food lovers, the pain of being unable to swallow in the late stage of esophageal cancer adds another layer of pain.

Why has China become a high-incidence area of ​​esophageal cancer?

The incidence of esophageal cancer in some areas of northern China was once the highest in the world. What life-saving insights can we draw from those counties and cities cursed by esophageal cancer?

Esophageal cancer is the most common

Globally, there are 604,100 new cases of esophageal cancer and 544,000 deaths each year[1]. According to the latest data released by the National Cancer Center, in China, there were 252,500 new cases of esophageal cancer and 193,900 deaths in 2016[2].

That is to say, 41% of new cases and 35.6% of deaths from esophageal cancer worldwide occur in China.

Asia is a region hardest hit by esophageal cancer, but even compared with geographically close Asian countries such as Japan and South Korea, our overall incidence rate is far ahead of others[3]; it is 100 times higher than that of developed Western countries[4].

However, this is not the scariest thing.

In the 1960s and 1970s, there was a dreaded "esophageal cancer high-incidence zone" near the Taihang Mountains in Henan, Hebei and Shanxi provinces.

The incidence of esophageal cancer in this area was once more than six times the national level and was the highest in the world[5].

The esophagus, the organ that is most closely related to eating, is deeply loved and also deeply hurt by the Chinese.

Why is this the case? First, drinking and smoking are two important risk factors for esophageal cancer[6][7], and China happens to be a country with a high incidence of tobacco and alcohol consumption[8][9].

About 36% of East Asians have facial flushing after drinking alcohol, and even drinking a little will cause facial flushing, nausea and headaches. People with this constitution are unable to metabolize acetaldehyde, a carcinogenic substance produced by alcohol in the body, which may be one of the reasons for the high incidence of esophageal cancer[10].

People who get drunk easily when drinking should limit their drinking rather than forcing themselves to drink, or have the unrealistic idea of ​​"training their drinking tolerance" by drinking small amounts multiple times, because this is not only likely to lead to sudden death, but also increases the risk of cancer in the long run.

For esophageal cancer, drinking a small amount of alcohol is not too dangerous. However, smoking and drinking are inseparable. A survey in Sichuan Province found that if people smoke and drink, their chances of developing esophageal cancer will be 8.86 times that of their peers[6].

China has more than 300 million smokers, consuming 40% of the world’s tobacco. In 2018, the smoking rate among Chinese men even reached an astonishing 50.5%[11]. Perhaps these cold numbers can give us a glimpse into why esophageal cancer is so prevalent.

Enlightenment from Taihang Mountains

However, drinking and smoking alone are not enough to explain the abnormally high incidence of esophageal cancer near the Taihang Mountains.

In Lin County, Henan Province, even the incidence of esophageal cancer in chickens is higher than elsewhere, which suggests that there must be some important carcinogenic factors in the environment or diet[12].

Since the 1970s, medical institutions have been working together to investigate the causes behind this. When researchers entered the lives of Lin County residents, what they saw must have been very horrifying.

First, there are molds on storage utensils and staple foods that have gone moldy under improper storage conditions. Residents here are accustomed to eating vegetables that are pickled and fermented in water, and the surface of the water is often covered with a thick layer of white mold. In the summer, people also drink fermented vegetable juice as a beverage[10]. Such moldy and pickled foods will produce carcinogenic nitrites[13].

Secondly, most residents get their water from dry wells and ponds. Most of this water comes from rainwater, mixed with domestic garbage and agricultural fertilizers, and is not clean in the first place. It is then stored in water tanks at home for a period of time before drinking. Therefore, in addition to food, high concentrations of nitrite are also present in drinking water[14].

Needless to say, people who like to eat pickled foods have a 9.44 times higher risk of developing esophageal cancer than the general population[15].

In addition, researchers have found that many residents here love to eat hot food, and some can even swallow 80-88 degrees Celsius hot food as a matter of course. It should be noted that eating too hot food is one of the risk factors for esophageal cancer. Studies have shown that people who like to eat hot food are 7.645 times more likely to develop esophageal cancer than the general population. [15]

After the reform and opening up, with the improvement of living standards and cognitive levels, the increase in the intake of vegetables and fruits, and the leap in food refrigeration methods, the Taihang Mountain region has finally gradually got rid of the curse of esophageal cancer.

The key to defeating esophageal cancer

Esophageal cancer is a hidden and dangerous disease. In the early stages, there are no special symptoms. Most patients seek medical attention because they feel difficulty swallowing. Once diagnosed, it is often found that the tumor has grown so large that it compresses and occupies the esophagus, which means it is already in the late stage[16].

As the tumor grows bigger, it becomes more difficult to swallow... Ordinary people simply cannot imagine the pain of patients who cannot eat or even swallow water.

Some people will undergo esophageal dilation, but the relief often only lasts a few days. A more long-term method is to place a metal stent in the esophagus to forcibly open the esophagus that has been squeezed and deformed by the tumor to barely allow food to pass through.

Currently, for esophageal cancer patients, their fate depends largely on the timing of discovery.

If the tumor is still in the early stages when it is discovered and can be removed surgically, the patient's 5-year survival rate can reach about 80% [7]; however, if the tumor is already in the late stages when the patient is diagnosed, the expected survival rate will drop to an extremely low level, with a 5-year survival rate of less than 5% [16].

Therefore, high-risk groups should undergo regular health screening to strive for early detection and early treatment.

Of course, the best way is to quit smoking and drinking, not eat moldy food, eat less pickled food, not eat hot food, change the single diet, and try to reduce the risk of esophageal cancer. These behaviors that cause harm from the mouth are discovered by our predecessors at the cost of their lives, and they are always warning us not to repeat the same mistakes.