S1238 Using an Endoscopic Full Thickness Resection Device to Obtain Histologically Complete Resection or Formal Staging in Patients with Previous Piecemeal Resection of Malignant Colon Polyps

Introduction: Benefits of polypectomy by endoscopic mucosal resection (EMR) include wide availability, short procedure time, and a low complication rate. Even larger polyps can easily be removed via piecemeal technique, though at the expense of clear resection margins. When polyps contain cancer and have unclear resection margins (Tx), the issue arises of how to best care for these patients. The standard of care approach for Tx polyps is surgical, to assess depth of invasion and stage lymph node involvement, given the over 10% risk of nodal involvement with level 2 submucosal malignant colon polyps. What is the endoscopist to do, other than surveillance, when the patient is either unfit for surgery or not willing to undergo surgery? The aim of this study is to evaluate the efficacy and utility of eFTRD of an EMR scar from a Tx malignant colon polyp, to properly stage or clear the resection margin in patients unwilling or unfit for surgery. Methods: After obtaining IRB approval, a retrospective analysis was performed at a tertiary care center from 2022-2023. Twelve adult patients with a history of piecemeal resection of a Tx malignant colorectal polyp were included. The exclusion criteria include non-malignant polyps, malignant polyps with clear resection margins, malignant polyps showing lymphovascular invasion (LVI) and surgical approach indicated. Variables collected include patient demographics, primary polyp histologic features, eFTR procedure efficacy, and adverse events (AE) (Figure 1). Results: Of the 12 cases reviewed, the mean age was 65.1 years and 67% male. Majority of the polyps were located in the rectosigmoid colon (91.7%). There was 100% technical success of eFTR with a mean procedure time of 42.7 minutes. At 6-month follow-up, there was no radiologic, endoscopic, or histologic evidence of recurrence. There were 2 cases with residual tumor found in the EMR scar on eFTR, 1 with negative margins and 1 with positive margins at the muscularis propria (T2) but negative LVI, who subsequently agreed to surgery. There was 1 AE reported 3 weeks after eFTR due to the clip falling out and causing bleeding per rectum, which did not require blood transfusions or endoscopic intervention (Table 1). Conclusion: This review represents the first study to assess the efficacy and safety of an eFTRD for nonsurgical management of Tx malignant colon polyps. Though a limited sample, early eFTR experience appears to be a safe and efficacious technique for endoscopic staging and margin clearance of these malignant polyps. Table 1. - Descriptive statistics of patient demographics, primary polyp features, and eFTR findings Ethnicity White 11 (92%) Hispanic/Latino 1 (8%) Primary Polyp Location Sigmoid 2 (17%) Rectum 8 (67%) Rectosigmoid 1 (8%) Transverse 1 (8%) Primary Polyp Histology Carcinoma within polyp 10 (83%) NET 2 (17%) Histologic Grade Well-differentiated 2 (17%) Moderately-differentiated 6 (50%) Poorly-differentiated 3 (25%) Data unavailable 1 (8%) Mean Polyp Size (mm) 22.7 Mean Scar Size (mm) 10.7 R0 resection 11 (92%) Residual cancer 2 (17%) T1a 1 T2 1 Benign radiology at 6 months 12 (100%) Nodes seen 2 (17%) Nodes w/ malignant classification 0 (0%) Adverse Events 1 (8%) Total 12 (100%) Figure 1.: Nonexposed endoscopic full thickness resection (eFTR) involves pulling the lesion into the scope cap (3), placing an over-the-scope clip to reconnect the serosal tissue (4), and using an electrosurgical snare to cut the lesion off (5). Mão de-Ferro S, Castela J, Pereira D, Chaves P, Dias Pereira A. Endoscopic Full-Thickness Resection of Colorectal Lesions with the New FTRD System: Single-Center Experience. GE Port J Gastroenterol. 2019 Jul;26(4):235-241.