Post written by Daan A. Verhoeven, BSc, and Hao Dang, MD, PhD, from Leiden University Medical Center, Leiden, The Netherlands.

In this meta‑analysis, we set out to evaluate how often local recurrence occurs following en bloc endoscopic submucosal dissection (ESD) of colorectal neoplasia when the horizontal margin is positive or indeterminate. We compared that risk to cases with a negative horizontal margin after en bloc resection.

ESD allows en bloc removal of larger colorectal lesions, enabling precise evaluation of tumor involvement at both the vertical and horizontal margins. According to the latest European Society of Gastrointestinal Endoscopy guidelines, positive or indeterminate horizontal margins (HM1/x) is considered a local-risk resection and typically warrants surveillance or further endoscopic intervention.

However, recent studies suggest that local recurrence after en bloc ESD with HM1/x may be relatively rare. This raises the question about the necessity of endoscopic surveillance for detecting local recurrence after en bloc ESD of colorectal neoplasms. Clarifying the risk of local recurrence in these cases is essential for optimizing patient management and tailoring follow-up strategies.

By pooling data from multiple smaller studies, this meta-analysis confirms that en bloc ESD with HM1/x is associated with a higher risk of local recurrence than with negative horizontal margins. Nonetheless, the absolute risk remains low—especially for noninvasive lesions—and the majority of recurrences are benign. Notably, invasive recurrences occurred only in lesions that were initially invasive or high-grade dysplasia.

These findings challenge the recommendation for universal strict surveillance of all HM1/x cases after en bloc ESD. Based on our results, we propose the following recommendations (figure). To minimize the risk of false-positive HM1/x, a sufficiently large margin of normal mucosa (>3-5 mm) should be included around the lesion during ESD, with careful endoscopic delineation of lesion boundaries. The use of image-enhanced endoscopy or chromoendoscopy can further improve diagnostic accuracy, and resection specimens should be pinned flat without overstretching to prevent curling or edge distortion.

Once the pathologist confirms HM1/x after careful specimen handling, the lesion’s histology should guide follow-up. More intensive surveillance is warranted for HM1/x lesions with invasive or high-grade dysplasia histology. Noninvasive lesions with low-grade dysplasia can generally be managed like R0-resected cases, unless the endoscopist suspects a residual macroscopic tumor. For these patients, we suggest a first surveillance colonoscopy at 3 years, followed by a second at 5 years if no significant abnormalities are detected.

Guideline recommendations for preventing and managing HM1/x cases. ESGE, European Society of Gastrointestinal Endoscopy; IEE, image-enhanced endoscopy; HM1/x, positive or indeterminate horizontal margins; R0, no residual tumor.

Read the full article online.

The information presented in Endoscopedia reflects the opinions of the authors and does not represent the position of the American Society for Gastrointestinal Endoscopy (ASGE). ASGE expressly disclaims any warranties or guarantees, expressed or implied, and is not liable for damages of any kind in connection with the material, information, or procedures set forth.