the purpose of this study is to evaluate application value of LCI in the diagnosis of early gastric cancer.

The detection rate of early gastric cancer is still very low in China. The investigators need a new and effective screening method to improve the detection rate. LCI (linked-color imaging)is a new model of laser endoscopy which can provide brighter image. LCI can provide clear image which can make red part redder and white part whiter, so suspicious lesion could be found easier. The study of this randomized controlled trial is to discuss effectiveness of LCI in the diagnosis of early gastric cancer and to find a new method to improve the detection rate of early gastric cancer in China.

Inclusion Criteria:

1. High-risk group of gastric cancer: H. pylori infection; previously suffering from chronic atrophic gastritis, intestinal metaplasia, gastric ulcer, gastric polyps, residual stomach after surgery, hypertrophic gastritis, malignant anemia and other precancerous diseases of gastric cancer;
2. First degree relatives of patients with gastric cancer;
3. There are other high risk factors for gastric cancer (high salt, salted diet, smoking, heavy drinking, etc.).
4. Patients with early gastric cancer treated with endoscopic therapy (ESD, EMR).
5. The informed consent has been signed.

Exclusion Criteria:

1. The TNM classification of cancer is consistent with those diagnosed by T2 above.
2. Patients with abnormal blood coagulation function or taking anticoagulants can not biopsy.
3. There were contraindications for gastroscopy.
4. A patient without self judgement;
5. Those who did not sign informed consent.
6. Previous gastroscopy has found suspicious lesions requiring careful examination.