Development of a new, minimally invasive, full thickness excision technique for early colonic neoplasia

Abstract

Introduction of bowel cancer screening programmes internationally has resulted in a significant shift in diagnosis towards early stage disease. In addition, the number of patients diagnosed with complex benign colorectal polyps is increasing. Advanced endoscopic techniques including endoscopic mucosal resection (EMR) and endoscopic submucosal dissection (ESD) as well as transanal endoscopic microsurgery (TEMS) are being increasingly utilised for excision of early rectal neoplasia. An equivalent surgical technique is currently not available for colonic lesions, and endoscopic techniques are associated with a high risk of complications such as bleeding, perforation and recurrence than in the rectum. Hemicolectomy with en bloc mesenteric excision remains the gold standard treatment for patients with early, node negative colon cancer and large colonic polyps. Even when performed laparoscopically within an enhanced recovery protocol, problems such as death, anastomotic leakage and other complications occurring in up to 40% of patients make colectomy a morbid intervention. The introduction to this thesis reviews the literature on the development and staging of colorectal cancer as well as currently available endoscopic and surgical techniques. In order to improve our understanding of the morbidity associated with hemicolectomy for the treatment of benign colonic polyps, two studies examined short term outcomes after surgery. The results suggest similar 30-day outcomes to those after cancer resection. In addition, a two-part study was designed to assess bowel function and related quality of life in patients who underwent hemicolectomy for colonic neoplasia, a subject that is poorly documented in the literature. As an introduction to the laboratory work, a systematic review of endoscopic full thickness excision techniques is presented. The final three chapters of the thesis describe ex-vivo development and outcome data after a porcine survival study of a laparo-endoscopic excision technique for colonic lesions as a potential alternative to hemicolectomy.