Author: Zhu Zhi (First Affiliated Hospital of China Medical University)
Numerous studies have found that, in general, stomach cancer does not develop directly from the normal gastric mucosal epithelium, but gradually evolves over a long period of time.
The period before the development of obvious clinical symptoms is called precancerous changes. According to the clinical situation and histopathological changes, the precancerous changes in gastric cancer are divided into two types: gastric precancerous state and gastric precancerous lesions.
1. The precancerous state of the stomach
Gastric precancerous state refers to some clinical conditions or diseases that lead to a significant increase in the risk of gastric cancer, mainly including the following aspects.
1. Chronic atrophic gastritis
Chronic atrophic gastritis is the most common disease in the precancerous state of the stomach, accounting for more than 2/3 of the precancerous state of the stomach. Because the incidence increases with age, it is mainly seen in middle-aged and elderly people.
Studies believe that the natural course of gastric cancer occurrence and development is normal gastric mucosa chronic superficial gastritis Chronic atrophic gastritis intestinal metaplasia of the intestinal epithelial metaplasia intestinal cancer. The cancerous rate of chronic atrophic gastritis in foreign countries is 8.6% to 13.8%, and in mainland China it is 1.2% to 7.1%[1].
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2. Stomach polyps
Stomach polyps are common and can be single or multiple. Histological types are divided into proliferative polyps (also known as non-neoplastic polyps) and adenomatous polyps.
Hypertrophic polyps are more common, mostly within 1.5 cm in diameter, rarely malignant, and some people have reported a malignant rate of only 1%.
Adenomatous polyps are rare, accounting for only about 10% of gastric polyps, are multiple single, have a potential risk of cancer, the total cancer rate is 15% to 40%, when its diameter is not less than 2 cm, the malignancy rate can be as high as 60%, especially the highest malignancy rate of villous adenomas [2].
After the malignant transformation of adenomatous polyps, it is mostly intestinal gastric cancer.
Clinically, it is believed that polyps with a diameter of not less than 2 cm, polyps with multiple polyps, and broad-based polyps with a larger base have a high rate of malignancy and should be paid full attention to.
3. Stomach ulcer
Stomach ulcers and stomach cancer have many things in common, but the relationship between the two has been controversial.
A domestic study based on 10,044 patients with gastric ulcers showed that the pathologically determined chance of ulcers developing pathologically determined carcinogenesis was only 2.1 percent, and that cancerous lesions occurred more in the mucous membranes around the ulcers than from the gastric ulcers themselves [1].
As of now, clinicians and pathologists have found no definitive evidence that ulcers turn into stomach cancer.
4. Gastric mucosal dysplasia
The gastric mucosa is characterized by atypical and abnormal differentiation of cells, and the mucosal structure is not sound, and there is a possibility of potential malignancy.
Depending on the history of ulceration, gastric mucosal dysplasia can be divided into low-grade dysplasia and high-grade dysplasia. Low-grade dysplasia diseases are stable in nature and have less impact on the human body; high-grade stunting is more prone to malignancy.
When gastroscopy reveals moderate to severe dysplasia, histological examination should be performed and followed up regularly.
5. Huge folds of the gastric mucosa
It is a rare disease in which serum proteins are missing through a large gastric mucosal fold, and the clinical manifestations are hypoproteinemia and edema. The rate of cancer in this disease is 10% to 13% [1].
6. Warty gastritis
The cause of this disease is unknown, and it is currently believed to be related to Helicobacter pylori infection, allergic immune response, high gastric acid secretion and other factors.
Some studies have shown that verrucous gastritis is closely associated with gastric cancer and should be considered a high-risk precancerous state [1].
7. After gastrectomy
Stomach disease may occur after surgical resection of stomach cancer. Foreign studies have found that the postoperative rate of gastric stump cancer can be as high as 5% to 16%, and the incidence of residual stomach cancer reported in China is 2.16% to 2.5% [2].
The occurrence of residual gastric cancer appears to be directly related to the postoperative interval, with a small number of cases occurring within 10 years of surgery, most of which occur within 10 to 20 years of surgery, and the population is mainly male, with a male-to-female ratio reported as high as 36:1 [2].
Most studies have concluded that postoperative residual stomach cancer has poor outcomes and a low 5-year survival rate.
2. Precancerous lesions of the stomach
Gastric precancerous lesions are a histopathological concept that are more likely to become cancerous than normal tissues or other pathological changes in the gastric mucosa, mainly including intestinal metaplasia and atypical hyperplasia.
1. Gastric mucosal intestinal epithelial metaplasia
Refers to the gastric mucosa of the innate glands in the pathological situation by the intestinal adenoid glands replaced (i.e., gastric mucosal epithelial cells replaced by intestinal epithelial cells), when stimulated to appear goblet cells that should be present in the intestinal epithelium and absorbing cells.
Depending on the histological changes, intestinal metaplasia can be divided into three subtypes: complete small bowel (type I), incomplete small bowel type (type II) and incomplete large bowel type.
Studies have confirmed that the risk of gastric cancer is far greater than that of incomplete gastric mucosal intestinal epithelial metaplasia than that of complete gastric mucosal intestinal epithelial metaplasia.
The probability of eventual development of gastric cancer in patients with intestinal metaplasia is approximately 0.25 percent [3].
2. Atypical hyperplasia
Also known as dysplasia, refers to abnormal proliferation of tissues and cells and poor differentiation, resulting in changes in morphology, structure and other changes in a type of lesion, histology between benign and malignant. Atypical hyperplasia of the gastric mucosa has a malignant tendency.
Timely detection of gastric precancerous state and precancerous lesions, strengthening regular recurrence and taking preventive measures can prevent or early detection of gastric cancer, which is why doctors often require patients to further examine or regularly re-examine.
bibliography:
[1] Yu Jieping, Wang Xiaozhong, Zhang Jiemei, etc. Diagnosis and treatment of gastric diseases[M].Beijing:People's Medical Publishing House.
[Xu Ximing,Zhou Zhongyin,Yang Jiyuan,et al. Diagnosis and treatment of malignant tumors of the digestive system[M].Science Press.
Fan Yaofu,Wei Muxin. Research progress and prevention and treatment countermeasures of gastric cancer precancerous lesions[J].World Chinese Journal of Digestion.2012(20).
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