Endoscopic En Bloc Versus Piecemeal Resection of Large Nonpedunculated Colonic Adenomas: A Randomized Comparative Trial

Background: Endoscopic resection of adenomas prevents colorectal cancer, but the optimal technique for larger lesions is controversial. Piecemeal endoscopic mucosal resection (EMR) has a low adverse event (AE) rate but a variable recurrence rate necessitating early follow-up. Endoscopic submucosal dissection (ESD) can reduce recurrence but may increase AEs.Objective: To compare ESD and EMR for large colonic adenomas.Design: Participant-masked, parallel-group, superiority, randomized controlled trial. (ClinicalTrials.gov: NCT03962868)Setting: Multicenter study involving 6 French referral centers from November 2019 to February 2021.Participants: Patients with large (>= 25 mm) benign colonic lesions referred for resection.Intervention: The patients were randomly assigned by computer 1:1 (stratification by lesion location and center) to ESD or EMR.Measurements: The primary end point was 6-month local recurrence (neoplastic tissue on endoscopic assessment and scar biopsy). The secondary end points were technical failure, en bloc R0 resection, and cumulative AEs.Results: In total, 360 patients were randomly assigned to ESD (n = 178) or EMR (n = 182). In the primary analysis set (n = 318 lesions in 318 patients), recurrence occurred after 1 of 161 ESDs (0.6%) and 8 of 157 EMRs (5.1%) (relative risk, 0.12 [95% CI, 0.01 to 0.96]). No recurrence occurred in R0-resected cases (90%) after ESD. The AEs occurred more often after ESD than EMR (35.6% vs. 24.5%, respectively; relative risk, 1.4 [CI, 1.0 to 2.0]).Limitation: Procedures were performed under general anesthesia during hospitalization in accordance with the French health system.Conclusion: Compared with EMR, ESD reduces the 6-month recurrence rate, obviating the need for systematic early follow-up colonoscopy at the cost of more AEs.Primary Funding Source: French Ministry of Health.