Low-grade intraepithelial neoplasia, after endoscopic resection, usually does not require complementary surgical procedures unless there is evidence of infiltrative manifestations. Low-grade intraepithelial neoplasia is a condition in which cells in the lower 1/3 of the layer within the epithelium show abnormal changes that resemble cancer cells, mainly because the structure and function of the cells are similar to those of cancer cells. However, the cells at this time are not cancer cells. If low-grade intraepithelial neoplasia develops throughout the epithelium, the cells at this time are cancer cells and are called carcinoma in situ. After endoscopic endothelial resection of low-grade intraepithelial neoplasia, other surgical procedures are usually not necessary because the abnormal cells at this time are neither cancerous nor break through the basal layer of the epithelium, and the risk of infiltration and metastasis is small. However, if there is an infiltrative foci in response to gross pathology performed after endoscopic resection, the decision for additional treatment needs to be made on an organ-by-organ basis.