“…The vast majority of lesions are easily treated by endoscopy, with a high complete resection rate. However, many lesions with depressions, congestion, erosions, or ulcers on the surface are cancerous, so EUS should be performed for a differential diagnosis and a determination of depth of invasion, 12 , 13 and biopsy tissues should be taken. When a tumor is judged to be malignant, endoscopic treatment becomes invalid, and further examinations by abdominal CT, MRI, or positron emission tomography (PET)-CT are necessary.…”