Colorectal cancer can be effectively prevented by removal of pre-malignant polyps during colonoscopy. Large (>=20mm) non-pedunculated colorectal polyps (LNPCPs) require careful assessment before treatment. If submucosal invasive cancer (SMI) is present, it determines whether endoscopic treatment can be curative or whether surgery is needed. Current classification systems to detect SMI are complex, require extensive training, and are underused in non-tertiary hospitals.

A simple web-based clinical decision support tool was created using well-established parameters (presence of a demarcated area, polyp size, Paris classification, location, and granularity) to identify SMI within LNPCPs. Crucially, the tool uses only standard endoscopic imaging available in most endoscopy units.

This prospective multi-centre study evaluates the accuracy of the tool during live endoscopic assessment. Endoscopists of varying experience will assess 10 large colorectal polyps using the tool, then undergo a randomized educational intervention (either a 10-minute instructional video or a 45-minute interactive training session). They will then assess a further 10 polyps using the tool. A third set of 10 assessments at 3 months evaluates durability of learning. Accuracy is compared to expert opinion.

Colorectal cancer (CRC) is a leading cause of death in the Western world. Large non-pedunculated colorectal polyps (LNPCPs, >=20mm) represent 2-3% of colorectal polyps and require special attention. The presence of submucosal invasive cancer (SMI) determines whether endoscopic treatment is curative or whether referral for surgery is necessary. Current endoscopic classification systems (JNET, Kudo, NICE) are complex, require specialized equipment, and extensive training, making them underused in non-tertiary practice.

A novel, freely accessible web-based clinical decision support tool (available at gieqs.com/SMI) was developed based on established risk factors for SMI: the presence and characteristics of a demarcated area within the polyp, polyp size (>=40mm), Paris classification, colonic location, and granularity. The tool uses only standard white-light and virtual chromoendoscopy available in the majority of Western endoscopy units.

This is a prospective, multi-centre study conducted across 8 centres in Belgium, the United Kingdom, Israel, and Italy. The study evaluates whether endoscopists of varying experience can accurately detect SMI within LNPCPs during live colonoscopy using this tool.

The study follows a pre-post design with randomization of the educational intervention:

• Phase 1 (Pre-training): Each endoscopist assesses 10 eligible LNPCPs using a standardized assessment and creates a 1-minute standardized video of each lesion.
• Educational Intervention: Endoscopists are randomly allocated (1:1) to either (a) a 10-minute non-dynamic instructional video or (b) a 45-minute interactive educational session.
• Phase 2 (Post-training): Each endoscopist assesses a further 10 LNPCPs using the clinical decision support tool.
• Phase 3 (Durability): At 3 months, a further 10 assessments are performed to evaluate durability of the training effect.

Expert opinion applied to standardized videos serves as the reference standard. Histopathology results are recorded for all resected specimens. An interim analysis is planned when half the required participants are enrolled.

Inclusion Criteria:

Endoscopist participants

• Gastrointestinal endoscopists of varying abilities and grades
• Endoscopists who have not previously encountered the clinical decision support tool Patient participants
• Referred for colonoscopy with appropriate bowel preparation
• Colorectal polyp >=20mm in size detected or referred for resection
• Non-pedunculated morphology
• Non-sessile serrated morphology
• Signed informed consent for the procedure and trial participation

Exclusion Criteria:

Endoscopist participants:

• Does not consent to inclusion
• Does not undergo the learning intervention
• No connection with endoscopy in gastroenterology

Patient participants:

• Does not consent to data collection for the study
• Video of inadequate quality as per opinion of the principal investigator

Patients with large (≥20mm) non-pedunculated colorectal polyps (LNPCPs) detected during colonoscopy or referred for endoscopic resection. Patients with sessile serrated lesions are excluded. Endoscopists must consent and complete the learning intervention. Patients must provide written informed consent for data collection. Participation is voluntary for both groups.