Endoscopic submucosal dissection (ESD) is an advanced technique of therapeutic endoscopy used for the removal of (superficial) gastrointestinal tumors. Superficial gastrointestinal tumors are tumors in the gastrointestinal tract in the early stages, when the cancer is limited to your stomach's superficial (uppermost) layers, nor has it spread to nearby lymph nodes or distant parts of the body. These tumors have not entered the muscle layer. The ESD technique has rapidly permeated in Japan for the treatment of early gastric cancer, due to its excellent results when compared to endoscopic mucosal resection (EMR the current procedure for tumor removal). Data from this study will be used for research purposes only to determine the clinical impact of endoscopic ultrasound removal of gastrointestinal tumors. Researchers will also be able to better understand the patient’s condition and disease process that may lead to improved standard of care and improved patient management for superficial gastrointestinal tumors.