ECDNA is almost non-existent in normal cells, but exists in nearly half of human cancer cells, indicating that studying such abnormal DNA is of great significance for our understanding of tumor formation and evolution. The changes in ecDNA expression in intestinal type gastric cancer may be closely related to the occurrence and development of gastric cancer. Dynamic monitoring of changes in ecDNA expression in the gastric mucosa may help predict the occurrence of gastric cancer and guide subsequent treatment. By collaborating with multiple endoscopic centers to conduct gastroscopy biopsies on patients with gastric precancerous lesions, we aim to further explore the role of ecDNA in the occurrence and development of gastric cancer through continuous follow-up.

Inclusion Criteria:

1. Age: 18-80 years old;
2. Patients who plan to undergo gastroscopy at the endoscopic center and patients who undergo surgical treatment for gastric adenocarcinoma;
3. Endoscopy doctors believe that pathological biopsy is necessary to clarify the pathological diagnosis;
4. No serious diseases or other systemic malignancies in terms of physical and mental health;
5. More than one item of non Atrophic gastritis, Atrophic gastritis, intestinal metaplasia, heterogeneous hyperplasia (low grade intraepithelial neoplasia and high grade intraepithelial neoplasia), and gastric adenocarcinoma;
6. Sign an informed consent form;

Exclusion Criteria：

1. Pathological results indicate other malignant tumors of the stomach, such as stromal tumors and lymphoma;
2. The patient and their family members do not agree to use the specimen for later research projects;
3. Before gastroscopy or surgery, neoadjuvant therapy or combined with other malignant tumors;
4. Non R0 resected gastric cancer patients;
5. Pregnant or lactating women;
6. Have a history of drug abuse such as alcohol and tobacco.

The population included in this study is mainly healthy patients who underwent gastroscopy at endoscopic centers, some of whom may develop gastric cancer during follow-up. At the same time, we will collect mucosal samples from volunteers who underwent gastroscopy but had normal gastric mucosa, and we will also collect gastric cancer tissue samples after surgical resection in our department