Whether or not to do gastroscopy to take tissue for biopsy, which is pathological examination, depends mainly on the presence and severity of lesions in the patient’s stomach, and on the other hand, the level of judgment and decision-making of the endoscopist. First of all, the patient factor. Whether the patient has lesions in the stomach, if the mucosa in the stomach is smooth, normal mucosal folds, normal color of the stomach wall, no congestion, no erosion and ulcer, then there is no need to take a biopsy for pathological examination. However, if the mucosa of the stomach wall is abnormal, but if it is common chronic superficial gastritis and mild ulcer, usually the endoscopist will give a diagnosis of chronic gastritis and gastric ulcer, and no biopsy will be taken. However, if the mucosal erosion and ulceration of the gastric wall is severe, a biopsy is needed to clarify the nature, whether it is a general inflammation or a cancerous ulcer. It should be noted that sometimes cancerous lesions and ulcers exist at the same time, and even if a biopsy is done and the pathological result is only reported as inflammation, if the endoscopist thinks the ulcer is not well presented, it is better to review the gastroscopy again after 2-3 weeks of oral medication for ulcers (omeprazole and gastric mucosal protector) to avoid missing the diagnosis of gastric cancer. In clinical practice, such cases are often encountered, and patients sometimes have 3-4 gastroscopic biopsies before the diagnosis of gastric cancer is confirmed. Another situation where biopsy is necessary is when an occupying lesion in the stomach is found. In layman’s terms, it means that something is found in the stomach wall, which may be benign, but of course, it may also be stomach cancer. At this time, a biopsy should be taken to clarify the nature and guide the treatment plan. However, there is one exception, that is, the swelling is not grown on the gastric mucosa, but grows under the mucosa, and the fluent mucosa is smooth, which is more commonly known as gastric mesenchymal stromal tumor (GIST), see the figure below. Once a mesenchymal tumor is suspected, a biopsy should not be taken, as it is prone to puncture and rupture, leading to metastasis and recurrence. There is also a doctor’s factor in taking or not taking a biopsy. It is mainly the doctor’s expertise, examination level and treatment experience. Experienced doctors, especially those who specialize in oncology, will be especially alert to the risk of cancer. When cancer is suspected, it is more likely to take tissue for pathological examination as a precaution. Especially in oncology specialty hospitals or hospitals with higher level of gastric cancer treatment, there are usually multiple endoscopic examination methods, such as magnifying endoscopy and staining endoscopy, to further clarify whether the risk of cancerous lesion is present, and the possibility of missing the diagnosis of gastric cancer will be small. In case of less experienced doctors, or general general hospital endoscopy rooms, the gastric diseases encountered are usually benign ulcers and inflammation, and even if mucosal changes in the stomach are seen, they are treated as general gastritis and gastric ulcers without biopsy, thus giving up the chance to detect early gastric cancer. Some people may say, what level, how can’t even distinguish gastric cancer from inflammation. Why? Because there is no obvious difference between early gastric cancer and general gastritis and gastric ulcer. There are only subtle changes. Only a higher level endoscopist may find certain differences by the shape, depth of ulcer, changes of mucosal folds and so on, and if he is alert, he will take biopsy. Early gastric cancer as shown in the picture is sometimes difficult to distinguish from gastric ulcer. Therefore, in clinical practice, many doctors are actively taking biopsies once they find changes in gastric mucosa. I agree with this, only in this way, it is possible to detect as many early gastric cancers as possible and reduce the rate of missed diagnosis.