Endoscopic Mucosal Resection and Endoscopic Submucosal Dissection.

Up to 15% of colorectal polyps are amenable for conventional polypectomy. Advanced endoscopic resection techniques are introduced for the treatment of those polyps. They provide higher en bloc resection rates compared with conventional techniques, while helping patients to avoid the complications of surgery. Note that 20 mm is considered as the largest size of a polyp that can be resected by polypectomy or endoscopic mucosal resection (EMR) in an en bloc fashion. Endoscopic submucosal dissection (ESD) is recommended for polyps larger than 20 mm. Intramucosal carcinomas and carcinomas with limited submucosal invasion can also be resected with ESD. EMR is snare resection of a polyp following submucosal injection and elevation. ESD involves several steps such as marking, submucosal injection, incision, and dissection. Bleeding and perforation are the most common complications following advanced endoscopic procedures, which can be treated with coagulation and endoscopic clipping. En bloc resection rates range from 44.5 to 63% for EMR and from 87.9 to 96% for ESD. Recurrence rates following EMR and ESD are 7.4 to 17% and 0.9 to 2%, respectively. ESD is considered enough for the treatment of invasive carcinomas in the presence of submucosal invasion less than 1000 μm, absence of lymphovascular invasion, well-moderate histological differentiation, low-grade tumor budding, and negative resection margins.