Diagnostic Accuracy of Deep Submucosal Invasion: White Light Endoscopy vs Invasive Pattern Based on NBI/BLI ± Chromoendoscopy

A video with the lesion assessment, without any data on the patient, will be recorded in a device connected to the processor provided by the Principal Investigator. The name of the file will be the record ID. All the lesions will be tested by the same endoscopist in vivo and an assistant will fulfill the data collection sheet during the colonoscopy.

First, the lesions will be cleaned and observed in a stable position. Size, location, morphology, demarcated areas, and gross morphological malignant features will be evaluated. Based on these WLE characteristics, a deep invasion prediction will be performed (control test). Second, the lesion will be assessed using NBI with near focus or magnification or BLI with magnification. A second cleaning with pronase (or N-acetylcysteine if pronase is not available) if the surface cannot be clearly observed because of the presence of mucus or if crystal violet is going to be used. Crystal violet 0.05% will be used in case of polyps type 2B in the JNET classification or lesions with a demarcated area. A non-traumatic catheter (or spray catheter) will be used to spray the crystal violet over the lesion. A final prediction of deep invasion will be performed for NBI or BLI ± CE (test evaluated).

The use of a cap to observe the bottom of the lesion, fix the lesion close to the endoscope or to observe the lesion underwater immersion is strongly recommended.

The resection technique will be decided upon according to the local experience. In case of endoscopy resection (cold snare, EMR, ESD, full thickness), lesions will be removed via the anus (not through the endoscopy channel) in order to preserve their integrity. Although EMR is performed, if possible, lesions will be referred to the pathologist well oriented and pinned out on a cork based, as is standard procedure in ESD.

In order to ensure that endoscopic assessment is performed before the histology evaluation, both diagnostic assessments (control test and test evaluated) will be recorded on the REDCap database on the day of the colonoscopy. REDCap records the time and date of all changes in the variables' results. The remaining variables (demographic data, etc.) will be recorded on the data collection sheet and copied later into REDCap.