Endoscopic mucosal resection and full-thickness resection of neoplastic lesions of the colon: clinical application and techniques—a narrative review

Background and Objective: Most small colorectal lesions can be effectively resected by endoscopists using standard polypectomy techniques. Large lesions may be difficult to remove and are associated with higher risks of complications and incomplete resection. Endoscopic mucosal resection (EMR) and endoscopic full-thickness resection (EFTR) are specialized endoscopic techniques developed for the resection of certain gastrointestinal lesions not amenable to standard polypectomy. In this review, we aim to discuss the basic principles, technical aspects, and limitations of performing colorectal EMR. We also provide an overview of the clinical applications and current evidence of EFTR. We also outline the principles to select the appropriate resection strategy for colorectal lesions. Methods: We searched original papers, reviews, and meta-analysis evaluating the technical and clinical applications of EMR and EFTR for colorectal lesions. Key Content and Findings: EMR is typically accomplished using a submucosal injection lifting the lesion away from the muscularis propria to allow for safe resection of the polyp. Despite its established advantages and safety, EMR cannot ensure complete resection of certain lesions with severe fibrosis and is associated with a relatively high recurrence rate. In addition, pathologic assessment of resection margins is limited due to fragmentation of the lesion. Endoscopic submucosal dissection (ESD) provides accurate pathological diagnosis with higher en-bloc and complete resection but is associated with a steep learning curve and prolonged procedure time. More recent variations of EMR such as tip-in EMR and pre-cut EMR allow higher en-bloc resection for certain lesions, with lower recurrence than conventional EMR and faster procedure time than ESD. However, certain lesions with severe submucosal fibrosis and early colorectal cancer cannot be resected effectively by EMR or ESD. In addition, both techniques cannot treat certain subepithelial lesions. EFTR is an emerging endoscopic intervention that enables transmural resection of gastrointestinal lesions, therefore overcoming the limitations of EMR and ESD. Conclusions: With the growth of the endoscopic armamentarium for colorectal lesions, surgical resection is currently rarely indicated. EMR remains the cornerstone for management of large colorectal lesions. EFTR has become a crucial addition to the endoscopic tools for resection further reducing the need for more invasive surgery.