NBI Versus Indigo Carmine During Colonoscopy in Lynch Syndrome (LYNCH-CHROMO)

Comparison of Colonoscopy With Virtual Chromoendoscopy Using 3rd Generation NBI System to Chromoendoscopy With Indigo Carmine in Lynch Patients.

This study compares two colonoscopy techniques (with Narrow Band Imaging versus with indigo carmine chromoendoscopy) in patients having Lynch Syndrome

Chromoendoscopy using indigo carmine dye is recommended every 1 to 2 years in patients having Lynch Syndrome (LS). However, it is a time-consuming procedure, requiring a prior learning and has an additional cost, the reason why it is not yet systematically practiced in all endoscopy centers. The "Narrow Band Imaging" (NBI) is a recent virtual chromoendoscopy technique using optical filters at the light source of the endoscope to highlight the vascular structures of the mucosa by pressing a button. NBI is currently used to better characterize dysplasia lesions in the esophageal, gastric, and colon mucosa. A new generation (3rd generation) of NBI is currently available on some endoscopes, it can deliver more brightness and contrast, and could allow for better detection of flat lesions. Until today, no study has directly compared colonic chromoendoscopy with Indigo carmine to virtual chromoendoscopy with NBI (3rd generation) in LS patients. The hypothesis that this research aims to verify is that the new generation NBI system might do at least as well as indigo carmine in colonic adenoma detection in LS. This study aims to compare colonoscopy with virtual chromoendoscopy using 3rd generation NBI system to chromoendoscopy with indigo carmine in LS patients, in a back-to-back, prospective non inferiority design, in which all patients will have both techniques in the following order: NBI first followed by Indigo carmine.

A double colonoscopy is performed in a back-to-back design using NBI chromoendoscopy then indigo carmine in each patient.

The adenoma detection rate (number of adenoma and/or adenocarcinoma) of NBI and the additional adenoma detection rate of indigo carmine.

Collect the number, size, location, endoscopic (Paris Classification) and anatomo-pathologic aspect (adenoma, hyperplastic polyp, adenocarcinoma) of all detected lesions with their respective prevalence.

Inclusion Criteria: Lynch Syndrome with an identified mutation in one of the genes MutL Homolog 1 (MLH1), MutL Homolog 2 (MLH2), MutS homolog6 (MSH6), PMS2 or epithelial cellular adhesion molecule (EpCAM) Age between 18 and 80 Indication of a screening colonoscopy Exclusion Criteria: Any sign of intestinal occlusion contra-indicating bowel preparation History of total or subtotal colectomy Any serious medical condition contra-indicating colonoscopy under general anesthesia Pregnant or breast feeding women Any coagulation disorder contra-indicating biopsies or endoscopic resections Any history of hypersensitivity to indigo carmine Adults subject to a legal protection measure (guardianship or curatorship)

Cellier C, Perrod G, Colas C, Dhooge M, Saurin JC, Lecomte T, Coron E, Rahmi G, Savale C, Chaussade S, Bellanger J, Dray X, Benech N, Le Rhun M, Barbieux JP, Pereira H, Chatellier G, Samaha E. Back-to-Back Comparison of Colonoscopy With Virtual Chromoendoscopy Using a Third-Generation Narrow-Band Imaging System to Chromoendoscopy With Indigo Carmine in Patients With Lynch Syndrome. Am J Gastroenterol. 2019 Oct;114(10):1665-1670. doi: 10.14309/ajg.0000000000000386.