Hydrogel Injection to Assist Endoscopic Submucosal Dissection

Inclusion Criteria: Patients must meet all of the following inclusion criteria in order to be entered into the study: A. Both genders of patients age 20 or older. B. Superficial tumors or polyps found either in esophagus, stomach, or large intestine via endoscopic diagnosis. C. Tumor or polyps ≧ 20 millimeters. D. Superficial tumor or polyps found either in esophagus, stomach, or large intestine have never received any kind of endoscopic treatment. E. No evidence of depth of submucosal invasion or metastasis via endoscopy. Exclusion Criteria: If patients meet any of the following criteria they may not be entered into the study: A. Patients suffering from other advanced malignant tumors. B. White Blood Cell\< 2000 μL or Severe thrombocytopenia（Platelet count \< 50,000 μL)，or blood coagulation abnormalities uncorrectable . C. Patients taking anti- thrombocytopenia or anti-coagulation medicine, and medication cannot be stopped under physicians' consideration. D. Main organs (heart, lung, liver, kidney) dysfunction who are not eligible for clinical trials under physicians' consideration. E. Evidence of depth of submucosal invasion or metastasis via endoscopy. F. Unable to follow-up by endoscopy. G. Unwilling to sign informed consent. H. Allergic to pharmaceutical excipients related to this medical device (Calcium Lactate or Sodium Alginate).