Indicators for early screening of gastric cancer include gastroscopy, as well as abdominal ultrasonography and abdominal CT examination, and may include pepsinogen examination and tumor index examination. Tumor index examination mainly includes CEA, CA199, AFP and CA125, because there is no specific tumor index for gastric cancer. If CEA or CA199 is high, it should be considered as possible lesions in the digestive system, possibly in the large intestine or pancreas, or possibly in the stomach. Gastroscopy is needed if the patient has symptoms of abdominal discomfort, such as vague pain, distension, burping, or even acid reflux, belching, black stools, etc. Because gastroscopy can also find out whether the lesions inside the stomach are caused by gastric cancer, gastric ulcer, or gastritis.