Recurrence rates after piecemeal endoscopic mucosal resection of large colorectal laterally spreading tumors.

Background: Piecemeal endoscopic mucosal resection (pEMR) is routinely employed for large laterally spreading tumors (LSTs). Recurrence rates following pEMR are still unclear, especially when cap-assisted EMR (EMR-c) is performed. We assessed the recurrence rates and recurrence risk factors post-pEMR for large colorectal LSTs, including both wide-field EMR (WF-EMR) and EMR-c. Methods: This was a single-center, retrospective study of consecutive patients who underwent pEMR for colorectal LSTs ≥20 mm at our institution between 2012 and 2020. Patients had a post-resection follow-up period of at least 3 months. A risk factor analysis was carried out using the Cox regression model. Results: The analysis included 155 pEMR: 51 WF-EMR and 104 EMR-c, with a median lesion size of 30 (range: 20-80) mm and a median endoscopic follow up of 15 (range: 3-76) months. Overall, disease recurrence occurred in 29.0% of cases; there was no significant difference in recurrence rates between WF-EMR and EMR-c. Recurrent lesions were safely managed by endoscopic removal, and at risk analysis lesion size was the only significant risk factor for recurrence (mm; hazard ratio 1.03, 95% confidence interval 1.00-1.06, P=0.02). Conclusions: Recurrence of large colorectal LSTs after pEMR occurs in 29% of cases. This rate is mainly dependent on lesion size, and the use of a cap during pEMR has no effect on recurrence. Prospective controlled trials are needed to validate these results.