Predictors of residual neoplasia after noncurative (R1) endoscopic submucosal dissection of lesions in the gastrointestinal tract.

Background: Endoscopic submucosal dissection (ESD) is a minimally invasive resection technique that enables the en bloc resection of gastrointestinal lesions. Despite en bloc resection, pathological evaluation of lesions can reveal positive vertical or horizontal margins, which is referred to as R1 resection. Not all R1 lesions referred for surgical resection or endoscopic surveillance show evidence of residual tumor. We aimed to identify the predictors of residual neoplasia in patients with an R1 resection following ESD.

Patients and methods: All lesions resected via ESD between June 2016 and September 2021 at a tertiary referral center were retrospectively identified. Lesions with an R1 resection and adequate follow-up were eligible for inclusion. Patient, lesion, and procedural characteristics were analyzed to identify predictors of residual neoplasia.

Results: Of 614 lesions, 163 (28%) had R1 resection. Of these, 56 lesions in 51 patients had complete follow-up and were included. Thirteen patients (25.5%) underwent surgical resection and the remainder underwent endoscopic surveillance. Seven (12.5%) patients had residual disease. All patients with residual disease had esophageal carcinoma. Positive deep and lateral margins, severe submucosal fibrosis, and moderate/poorly differentiated tumors were identified as significant predictors of residual neoplasia.

Conclusion: Most R1 lesions (87.5%) resected by ESD did not have residual disease on follow-up. Those without identified risk factors for residual disease, such as esophageal carcinoma, severe submucosal fibrosis, or both histological margin positivity, may benefit from a strategy of close endoscopic surveillance rather than referral for surgical resection.