Since the 1960's, endoscopy has revolutionised the practice of gastroenterology. Although initially diagnostic, endoscopy is now playing an increasingly therapeutic role. There are many reasons to believe that therapeutic endoscopy will shape the practice of gastroenterology further in the future. Only a few years ago we relied on low-resolution fibreoptic endoscopes. Nowadays even standard equipment allows the mucosa to be scrutinised in great detail. Dedicated training in endoscopy together with attention to quality indicators such as polyp detection and caecal intubation rates will ensure that fewer early gastrointestinal cancers are missed in the future. Open access endoscopy and screening programs are being introduced in many Western countries which will also lead to more lesions being detected in their early stages. This chapter discusses the main issues surrounding the endoscopic therapy of lower gastrointestinal cancers.