The Relationship Between Scar Formation and ESD Depth in Therapy for Gastric Carcinoma

Inclusion Criteria: * Patients older than 18 years old and younger than 75 years old. * Early gastric cancer (T1a stage) diagnosed by gastroscopy or ultrasonography, differentiated and no ulcer; or early gastric cancer (T1a stage), differentiated with ulcer, lesion diameter \<3cm; or early gastric cancer (T1a stage), undifferentiated and No ulcer, lesion diameter \<2cm. * Pathological diagnosis of gastric cancer. * No further treatment is required. * Patients diagnosed for the first time without other serious gastrointestinal diseases. Exclusion Criteria: * Those who did not comply with the test requirements, obviously violated this protocol, or switched to other protocols in the middle of treatment. * Advanced gastric cancer; or undifferentiated gastric cancer lesions \> 2 cm in diameter; or differentiated gastric cancer with ulcer lesions \> 3 cm in diameter. * Coagulation disorders. * Serious heart, liver, kidney and other diseases, can not tolerate ESD treatment. * Patients with gastric cancer complications such as gastrointestinal bleeding and perforation that need emergency treatment. * Patients with distant metastasis. * Patients with other tumors, patients with a history of malignant tumors (except early carcinoma in situ. * The patient himself requests to withdraw from the trial. * The researcher believes that the patient is not suitable to participate in this study.