Roel Bogie

Development and validation of an educational web-based system for endoscopic classification of laterally spreading tumors

Introduction Laterally Spreading Tumors (LSTs) are large flat colorectal neoplasms which can be resected with minimally invasive procedures, i.e. endoscopic mucosal resection (EMR) or endoscopic submucosal dissection (ESD), thereby avoiding surgery. 1, 2 Four endoscopic subtypes have been described: homogenous granular subtype (LST-G-H) which displays regular and equally sized granules on the surface; nodular mixed granular subtype (LST-G-NM) which displays a granular surface with at least one dominant nodule (sessile component); flat-elevated non-granular subtype (LST-NG-FE) which displays a completely flat and smooth surface; and pseudo-depressed non-granular subtype (LST-NG-PD) which displays a flat and smooth surface with a superficial indentation. 3 Using this endoscopic classification of LSTs is of critical importance since the risk of containing submucosal invasion (SMI) varies between subtypes, 4 guiding the preferred method of resection. 5, 6 Colorectal neoplasms in general are classified using the Paris classification. 7, 8 This classification is less useful for LSTs because it cannot distinguish between granular and non-granular subtypes. The overall agreement when applying the Paris classification among colonoscopy experts was only fair to moderate in a single study and did not improve after a short training. 9 Practical clinical guidelines propose a lesion-specific approach for treatment of LSTs. 2, 6, 10 To implement these guidelines in clinical practice, the Kudo endoscopic classification of LSTs requires good interobserver agreement (IOA) and at first has to be validated. Few studies addressed the IOA in using the endoscopic Kudo classification, 11, 12 and none tested this among international colonoscopy experts. Training of endoscopists has to be provided on applying this classification. In the current study we gathered a photo collection of LSTs, validated the endoscopic Kudo LST classification among international colonoscopy experts and developed and validated an e-learning on LST classification. The aims of this study were (I) to examine whether the Kudo LST classification is a useful tool in practice; (II) to test whether an e-learning on LST classification is effective among trainees. Furthermore, we explored the IOA in the application of the Paris classification on LSTs and in selecting the most suitable treatment strategy among colonoscopy experts. Material and Methods We employed the Guidelines for Reporting Reliability and Agreement Studies (GRRAS). 13 We conceived the study using a stepwise approach as displayed in Figure 2.1 . Definition of LST LSTs were defined as non-polypoid colorectal neoplasms (NP-CRNs) at least 10mm in diameter which grow mainly laterally along the mucosal wall instead of growing only upward (luminal) or only downward (submucosal). 3, 14 The endoscopic LST Kudo classification has four subtypes: LST G-H (regular surface, evenly-sized granules), LST-G-NM (granular surface with at least one dominant nodule [sessile component]), LST-NG-FE (completely flat surface) and LST-NG-PD (smooth surface with subtle indentation) ( Figure 2.2 ). Development phase The core group investigators (HMC and LC, National Taiwan University Hospital [NTUH] and SS and RB, Maastricht University Medical Centre [MUMC+]) selected the LST cases that were diagnosed at the endoscopy units of the academic centers (Figure 2.1 , step 1). A total of 103

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