SLND Versus Non-Dissection Following ESD for T1a Stage Esophageal Squamous Cell Carcinoma

Inclusion Criteria: * Clinical stage T1aN0M0. * A lesion detected on Endoscopic Ultrasound featured as T1a stage. * Age 18 to 75. * Patients who have signed the informed consent form. Exclusion Criteria: * • Other than invasive adenocarcinoma by pathological analysis. * Not complete resected or curative intent. * Patients who have history of other malignant tumors. * Patients who have history of thoracic surgery. * Patients who have received radiation, chemotherapy or other treatments previously.