The most important examination to confirm the diagnosis of gastric cancer is gastroscopy, through which the situation inside the stomach can be directly seen. If a suspicious mass is seen in the stomach, a biopsy can be done directly to make a clear diagnosis through pathological examination and determine whether it is a common gastric ulcer or a malignant tumor in the stomach. Besides gastroscopy, patients can also undergo H. pylori examination, abdominal MRI examination, and tumor marker abdominal CT examination to observe the condition of perigastric lymph nodes and the relationship between stomach tumor and surrounding tissues.