Gastric cancer is mainly related to seven factors! Why is it difficult to detect gastric cancer in its early stages through symptoms?

Author: Liang Bin, Chief Physician, Peking University People's Hospital

Reviewer: Tian Bei, Chief Physician, Beijing Tongren Hospital, Capital Medical University

my country is a country with a high incidence of gastric cancer. Among all tumors, the incidence and mortality of gastric cancer rank second and third respectively.

Gastric cancer is the result of the combined action of multiple pathogenic factors.

First, it is related to geography. Globally, about 40% of gastric cancer cases originate from my country, while the incidence of gastric cancer in Japan and South Korea is also relatively high.

Second, it is related to eating habits. For example, frequent intake of pickled foods, leftovers, and leftovers usually contain high concentrations of nitrites, which are converted into nitrosamines under the action of appropriate acidity, temperature, and microorganisms. Nitrosamines are a clear carcinogen. In addition, frequent consumption of barbecued foods can also increase the risk of gastric cancer, because barbecued foods contain polycyclic aromatic hydrocarbons, which are also a clear carcinogen.

Third, it is related to smoking. The incidence of proximal gastric cancer in Western countries is slightly higher than that in my country. Studies have found that the occurrence of proximal gastric cancer may be related to gastroesophageal reflux and smoking.

Fourth, it is related to genetic factors. For example, if there is a stomach cancer patient in the family, it will increase the risk of their children or descendants suffering from stomach cancer.

Fifth, it is related to living conditions. For example, if the living standard is high and fresh vegetables, fruits, and meat are often eaten, eating fresh food may be a good protective factor. In countries or regions with relatively poor living conditions, the probability of consuming fresh food is lower, and the incidence of gastric cancer may also be relatively higher. Therefore, the level of living standards will also affect the incidence of gastric cancer.

Sixth, it is related to Helicobacter pylori infection. Helicobacter pylori can damage the protective layer of the gastric mucosa, making peptic ulcers more likely to occur. The repeated damage and repair of peptic ulcers will increase the chance of canceration, and the chance of gastric ulcer canceration is basically between 1% and 5%.

Seventh, it is related to precancerous lesions. Precancerous lesions include chronic atrophic gastritis and gastric polyps. Different types of gastric polyps have different chances of becoming cancerous. If you find gastric polyps, you should go to a regular hospital for diagnosis and treatment. The presence of intestinal metaplasia and severe atypical hyperplasia in chronic atrophic gastritis indicates that it has reached the level of precancerous lesions.

Figure 1 Original copyright image, no permission to reprint

All of the above factors are related to the occurrence of gastric cancer.

Early gastric cancer is generally difficult to detect through symptoms because early gastric cancer generally has no symptoms.

The stomach is a pouch-like structure, connected to the esophagus above and the duodenum below. The pylorus and cardia are relatively small structures, in the shape of small tubes, with a "big bag" in the middle, which is the body of the stomach. If a tumor grows in the pylorus or cardia, it may affect eating as the tumor grows. For example, if the tumor grows in the pylorus, food cannot be emptied into the duodenum, and you will feel bloated; if the tumor grows in the cardia, food cannot go down when you eat; if the tumor grows in the body of the stomach, because the body of the stomach is relatively large, symptoms may not easily appear before the tumor grows to a certain size. Sometimes you may feel a little mild indigestion, bloating, and abdominal pain, which are all non-specific symptoms. Therefore, gastric cancer is not easy to detect early through symptoms.

Figure 2 Original copyright image, no permission to reprint

How can we detect gastric cancer early? Screening is very important, such as serological tests, gastrointestinal imaging, electronic gastroscopy, etc., which may detect some small or relatively early gastric cancers before symptoms appear. The following groups of people should undergo regular gastric cancer screening.

First of all, age is an important factor. For people with no family history of cancer, family history of gastrointestinal cancer, or family history of gynecological cancer, it is usually recommended to start gastrointestinal cancer screening at the age of 40, including gastroscopy and colonoscopy. If there is a family history of cancer, the screening age should be advanced by 5-10 years, especially if there is early-onset gastric cancer or colorectal cancer in the family. If the onset age of gastric cancer or colorectal cancer in a direct relative is in the seventies or eighties, it is mostly sporadic and has little correlation with genetics. When a direct relative suffers from gastric cancer or colorectal cancer in his fifties or sixties, this early-onset case is more closely related to genetics, so it is recommended that his descendants and direct relatives should be screened as early as possible.

Second, people with high-risk factors, such as chronic atrophic gastritis, gastric polyps, and Helicobacter pylori infection, should be screened more frequently and earlier.