Detection and Classification of Colon Polyps

Overview

Colon cancer is the third most common cancer in western society. To prevent colon cancer it is recommended for people to undergo a screening colonoscopy at the age of fifty. The purpose of the colonoscopy is to remove polyps, since some of these lesions are precancerous. Precancerous polyps are called adenomas. This method of prevention is effective, but the standard colonoscopy currently used does not detect all polyps. Studies have reported a polyp miss rate of about 24%. Furthermore, we are unable to distinguish precancerous polyps from benign polyps, also known as hyperplastic polyps, with standard colonoscopy. This results in all polyps being removed at time of colonoscopy, even the benign polyps. To help improve the detection of colon polyps new endoscopic technologies have been developed. These technologies include high definition white light (HDWL)and high definition narrow band imaging (HDNBI). HDWL improves the overall resolution of the images seen during colonoscopy. HDNBI can help us better classify polyps by enhancing their tissue appearance as well as seeing small blood vessels and capillaries. The goal of this study to determine if HDNBI imaging shows an increased polyp detection rate when compared to the current standard colonoscopy. In addition to develop a classification system to help better differentiate between precancerous polyps and their benign counterparts using HDWL and HDNBI.

II. Hypothesis: 1. The use of NBI colonoscopy will reduce the miss rate for colon polyps compared to standard white light imaging. 2. HDWl and HDNBI are more accurate than standard colonoscopy for the classification of adenomatous polyps in comparison to other non-premalignant polyps. III. Specific Aims: 1. Compare the miss rate of standard white light imaging compared to NBI for detection of colon polyps with NBI 2. Estimate the accuracy of standard white light, HDWL and HDNBI imaging modes for the classification of adenomatous (premalignant) versus non-adenomatous (hyperplastic, inflammatory, normal) polyps. 3. Examine the inter-observer agreement for classification of adenomatous versus non-adenomatous polyps based on standard, NBI and HDWL imaging. IV. Research Design and Methods: 4.1 Study Design: A prospective phase II cross-over trial. Patients will undergo both procedures (standard, NBI) back to back under conscious sedation. The order of the procedure will be randomized. 4.2 Setting: The study will take place at Mayo Clinic Jacksonville, Division of Gastroenterology, an expert center in the diagnosis and treatment of colon polyps. 4.3 Study Subjects All patients scheduled for colonoscopy at Mayo Clinic Jacksonville will be screened for eligibility using inclusion and exclusion criteria. The patients that are deemed eligible will be offered participation in the study. Informed consent will be obtained and the participant will be registered in our database. Prior to consent the participant will be made aware of the investigative nature of the study, alternatives, risks, and benefits. 4.4 Eligibility Criteria Inclusion Criteria: 1. Age 18 years or older. 2. Informed written consent. Exclusion Criteria: 1. History of inflammatory bowel disease. 2. Patients with severe cardiopulmonary disease precluding colonoscopy. 3. Presence of conditions not allowing for polypectomy or biopsy (e.g. coagulation disorder). 4. Known familial polyposis syndrome (FAP, HNPCC, Juvenile polyposis, etc) 5. Sub-optimal preparation for the procedure, which will be determined by patient history or based on the initial colonoscopy. 6. Pregnancy 4.5 Procedure and Data Collections A. Pre-procedure: All patients will be prepared for colonoscopy with the standard preparation and will be scheduled to have the procedure at Mayo Clinic Jacksonville. The principal investigator (PI) will screen eligible patients based on medical history, physical exam and laboratory data on day of procedure. Patients typically arrive at the registration area at least 60 minutes before start of scheduled procedure. A GI endoscopy nurse will prepare patients in the standard manner and intravenous access will be placed. Eligible patients will be offered informed consent by the study PI or designee. Patients who agree to participate in the study will sign informed consent and will be registered in the database. A log with only non-identifiable (e.g. patients # 1) will also be maintained of eligible patients who decline to participate. The GI endoscopy nurse will monitor patient's vitals before, during and after procedure as per standard protocol. B. Procedure: The exams will be performed back to back with a standard colonoscope and an ETMI colonoscope provided by Olympus. The order of the first and second procedure will be randomized according to a list prepared by the statistician using randomly permuted blocks to ensure equal numbers of patients are randomized to the two groups. All patients will be sedated with meperidine or fentanyl and midazolam to achieve conscious sedation. Each procedure will be preformed by a different endoscopist. The endoscopist will be either the P.I. supervised by a GI staff physician or solely by one of the five GI staff physicians. During the initial colonoscopy all visualized polyps will be noted, photographed, and removed. When the ETMI colonoscope is used, all polyps will be photographed using these modes (HDWL, HDNBI). The NBI portion of the exam will be performed using the MB-046 cap to further enhance stabilization of the focal length of the colonoscope. The second procedure will be done with the same level of careful inspection as the first although we not specifically regiment the time of withdrawal beyond what the endoscopist feels is necessary for a careful examination. During the second colonoscopy all visualized polyps will be noted, photographed and removed. During the first procedure, the time will be evaluated with a stopwatch. The stopwatch will start when the endoscopist begins pull-back at the cecum and end when the scope is removed from the anal verge. The clock will be stopped during washing of the bowel, polypectomy, biopsy or any other therapeutic maneuver. At the end of the first procedure, the endoscopist will be informed of the withdrawal and inspection time and every effort will be made to match this to the second procedure. Time will be recorded similarly for the second procedure. Polyps will be classified as pedunculated, raised-sessile (rounded) or flat. Flat polyps will be further classified according to the Paris endoscopic classification 14. C. Post-procedure: After the procedure all patients will be brought to the recovery and monitored as per standard protocol. Participants will be given discharge instructions as per protocol and also be provided with information to contact the P.I. if any problems should occur. Any post procedure complication will be reviewed on weekly intervals.