Lower Lugol's Solution Concentration on Reducing the Adverse Symptoms of Chromoendoscopy With Iodine Staining

Inclusion Criteria:

* patients in the high-risk population of ESCC;
* or general risk population of ESCC between 40 to 74 years old. Definition of high-risk population of ESCC is list in supporting information33.

Exclusion criteria included the following:

* with obvious abnormalities in stomach, confirmed by either white-light endoscopy (WLE) or pCLE, including gastric cancer, acute erosive and hemorrhagic gastritis, chronic atrophic gastritis, H. pylori infection and severe bile reflux gastritis;
* advanced esophageal carcinoma;
* known esophageal surgery or endoscopic treatment;
* known esophageal radiotherapy or chemotherapy;
* esophageal stenosis;
* food retention;
* allergy to iodine or fluorescein sodium;
* hyperthyroid;
* coagulopathy;
* acute bleeding;
* severe organ failure;
* pregnant or breastfeeding women.