Gastroscopy is very important in the examination of gastric cancer, and taking a biopsy under gastroscopy is an important means of diagnosis. Other examinations include endoscopic ultrasound or enhanced abdominal CT and chest CT to assess the staging of the patient. With endoscopic ultrasound, we can see which layer of the stomach wall the tumor has invaded and then combine it with chest and abdominal CT scans to assess whether there is distant metastasis. Diagnosis requires gastroscopy with a biopsy taken during the procedure.