Cold Snare Polypectomy

Colorectal cancer (CRC) is a major global disease affecting more than 1 million people worldwide and the majority of colon cancers develop from adenomas. The purpose of endoscopic cancer prevention is the detection and removal of these precancerous adenomatous polyps. However, polyps between 4-20 mm are incompletely eliminated in about 10% of cases, which is one of the main risk factors for patients to develop post-colonoscopy cancers. The polypectomy with cold snare showed promising results for complete adenoma resection rates for polyps up to 9 mm. The hypotheses is that polypectomy with cold snare could be a standard approach for polyps up to 20 mm and could improve the rates of complete resection of the adenoma. All eligible patients to undergo colonoscopy will be considered for the project. Patients will be identified from the colonoscopy appointment lists at the CHUM. During colonoscopy, the endoscopist will document prospectively all polyps detected and note the size, location and morphology. All polyps will be removed during the procedure and will be sent to the laboratory as recommended in current clinical practice. Polyps of 4-20 mm will be removed only in accordance with the method the cold snare. Afterwards, the remaining tissues could be observed with an imaging technology called Optivista with an injection of 10-50 ml of saline solution (ir required) to improve visibility of the tissues. Optivista is an imaging technique based that uses a light filter for endoscopic optical diagnosis where light of specific blue and green wavelengths is used to enhance the surface and vascular patterns of the polyp surface mucosa. The intestinal mucosa will be carefully examined and the endoscopist will continue to remove the remaining polyp tissue (with a snare or forceps) until there are no more visible polyp tissues. Biopsies from the polyp resection site will be sent to the laboratory for analysis to confirm the complete resection. Telephone follow-up will be done 14 days after the procedure to report possible side effects occurred. The rate of incomplete resection of all adenomatous polyps resected in the cold snare will be determinate after completion of this project. The confidence interval will first be calculated using the exact confidence limits of Clopper-Pearson, considering all adenomatous polyps. An additional analysis will also be performed with a model of estimation equations (GEE) based on the binomial distribution to obtain standard errors taking into account the correlation with the patient.