Profylaktisk dobbel termisk ablasjon og fullstendig lukking etter endoskopisk slimhinnereseksjon av store ikke-pedunkulerte kolorektale polypper: et randomisert kontrollert forsøk (ABLATION)

Standard endoscopic mucosal resection (EMR) technique will be used for the primary removal of all polyps, utilizing submucosal injection. Electrocautery snare technique will be facilitated using standard microprocessor-controlled electrocautery (e.g., ERBE VIO Endocut 3-1-6). Ablation of the margin and base of the polypectomy site will be performed using Hybrid Argon Plasma Coagulation (h-APC, Erbe Hybrid APC).

The hybrid argon plasma coagulation (h-APC) combines an ablation technique (APC) with the option for submucosal saline injection using a high-pressure water jet. The technique allows for the lifting of dysplastic epithelium, creating a cushion under the mucosa to facilitate the ablation of larger areas more thoroughly and with higher energy settings, while posing a low risk for side effects or complications.

• h-APC

Standard endoscopic mucosal resection (EMR) technique will be used for the primary removal of all polyps, utilizing submucosal injection. Electrocautery snare technique will be facilitated using standard microprocessor-controlled electrocautery (e.g., ERBE VIO Endocut 3-1-6). Ablation of the margin of the polypectomy site will be performed using Snare tip soft coagulation (STSC).

The Snare tip soft coagulation (STSC) involves using a snare to remove polyps, while simultaneously applying soft coagulation to the surrounding tissue using a specialized tip on the snare.

• STSC

Lesion recurrence at first follow-up after EMR of large (≥20mm) colorectal LSLs when performing STSC margin ablation or h-APC margin and base ablation. Defined by visual recurrence or pathology-confirmed hyperplastic, serrated or adenomatous histology of the same histology of the index lesion at the tattooed resection site on at least one of four random biopsies of resection scars. These will be evaluated from an intention to treat and per protocol standpoint.

Adverse event rates after EMR of large (≥20mm) colorectal LSLs when performing EMR with STSC margin ablation or h-APC margin and base ablation. Defined as either a) delayed bleeding (defined as blood per rectum resulting in emergency room visit, unplanned hospitalization; endoscopic, radiologic, or surgical intervention) or b) delayed perforation (defined as endoscopic or radiologic evidence of air or luminal contents outside the gastrointestinal tract). These will be evaluated from an intention to treat and per protocol standpoint.

Technical success of STSC or h-APC defined as achieving a complete uninterrupted ring ofcircumferential margin ablation for STSC and h-APC, without crossover to complete the margin ablation, and achieving 100% surface ablation of the resection base for h-APC.

Lesion recurrence at the 18-month follow-up after EMR with STSC or h-APC

High-grade dysplasia or colorectal cancer occurence after EMR during the 18-month follow-up period at the resection site.

CRC occurrence after EMR during the 18-month follow-up period

Colonoscopies required to achieve lesion clearance, defined as no histologic recurrence at the resection scar on follow-up.

EMR procedure time with STSC or h-APC

Defined as no surgical resection performed.

Defined as blood per rectum resulting in emergency room visit, unplanned hospitalization; endoscopic, radiologic, or surgical intervention. Proximal defined as proximal to the splenic flexure.

Defined as blood per rectum resulting in emergency room visit, unplanned hospitalization; endoscopic, radiologic, or surgical intervention. Distal defined as splenic flexure and distal.

Defined as blood per rectum resulting in emergency room visit, unplanned hospitalization; endoscopic, radiologic, or surgical intervention.

Delayed perforation defined as endoscopic or radiologic evidence of air or luminal contents outside the gastrointestinal tract

Any delayed bleeding after EMR, defined as blood per rectum after the procedure

Defined as adequate apposition of the mucosal defect margins without visible submucosal areas >3 mm along the closure line.

Lesion recurrence at first follow-up after EMR of large (≥20mm) colorectal LSLs when performing STSC margin ablation or h-APC margin and base ablation. Defined by pathology-confirmed hyperplastic, serrated or adenomatous histology of the same histology of the index lesion at the tattooed resection site on at least one of four random biopsies of resection scars. Factors such as age, sex, lesion size (20-29mm, ≥30mm; 20-39mm, ≥40mm), histology, location, difficulty (difficult defined as peri-appendiceal, on the ileocecal valve, resection previously attempted and failed by a referring endoscopist), use of epinephrine in submucosal injection, submucosal lifting solution, resection type (en bloc [i.e. in one piece] vs piecemeal), technical success, study site, endoscopist yearly EMR volume, presence of intraprocedural bleeding, utilization of adjunct resection methods, ileocecal or anus involvement, polyp histology/morphology will be evaluated.

Adverse event rates after EMR of large (≥20mm) colorectal LSLs when performing EMR with STSC margin ablation or h-APC margin and base ablation. Defined as either a) delayed bleeding (defined as blood per rectum resulting in emergency room visit, unplanned hospitalization; endoscopic, radiologic, or surgical intervention) or b) delayed perforation (defined as endoscopic or radiologic evidence of air or luminal contents outside the gastrointestinal tract). Factors such as age, sex, lesion size, morphology, histology, location, complete/incomplete/no defect closure, prophylactic vessel ablation, base ablation, anticoagulant use will be evaluated