Detection of Endoscopic Resection Scars and Delineation of Recurrence Amongst Non-experts is Less Accurate Than Experts But Trainable in a Short Learning Intervention

Colorectal cancer is prevented by colonoscopy and polypectomy. Failure to recognize the endoscopic resection scar after Endoscopic Mucosal Resection (EMR) risks unrecognized recurrent or residual adenoma (RRA), which may propagate into post-colonoscopy colorectal cancer. Expert series suggest scar recognition and interrogation is well performed with a high negative predictive value of endoscopic imaging vs histopathology. In this study the authors will investigate the performance of endoscopic imaging in detecting RRA at an endoscopic resection scar amongst general endoscopist and the impact of a learning intervention on recognition of RRA.

After consent is given, the participant will open the online survey and fill this in.

First the participant will be asked to create a pseudonym (name+year of birth) and fill in their demographical information (Grade, years in current role, colonoscopy experience, experience of colonic tissue resection, country of employment

The first 15 pictures will be shown prior to a learning intervention. For each picture the same questions will be asked:

• Is this an endoscopic resection scar?
• Based on this image does the scar demonstrate evidence of residual or recurrent adenoma (RRA)?
• What is your level of confidence?
• If the scar shows RRA, how would you treat it? (skip if you feel no RRA).
• If the scar does not show RRA do you feel there is another diagnosis? After the first 15 pictures a video-based learning tool will be shown on detection of RRA.

After the learning tool 15 different pictures will be shown, the same questions will be asked. All responses will be collected by the investigators. Statistical analysis will be performed using visual studio code (Microsoft, Redmond, USA) Images will be selected from the 'Australian Colonic LSL Endoscopic Resection Study' (ACE) database, which is an international multicentre registry of images and videos for retrospective analysis of colonic lesions. Images, videos, procedural information, and histopathological data are stored on a secure online web portal after written informed consent of every participating patient.