This document discusses endoscopic full-thickness resection (EFTR), a new endoscopic technique for removing subepithelial tumors without extraluminal growth. EFTR allows complete resection of tumors while minimizing risk of residual tissue and improving pathological diagnosis. It is best suited for skilled endoscopists treating large or submucosal tumors in the upper or lower GI tract. The procedure requires a team of trained medical staff, specialized instruments for resection and closure, and carries several challenges around promotion, training and device development to further improve outcomes.