Endoscopic Intermuscular Dissection – short-term outcomes

Abstract Introduction To evaluate the feasibility and outcomes of endoscopic intermuscular dissection (EID), we present a case series of patients with suspected deep submucosal invasive T1 rectal cancers based on pre-interventional assessment. The aim is to describe the potential role of EID within risk-adapted treatment strategies for early rectal cancer. Methods EID was performed in sixteen patients at the University Hospitals Augsburg and Bochum. En bloc resection was achieved in all cases. In six patients, the resection site was closed using the Olympus SutuArt hand-suturing device (Olympus, Tokyo, Japan) Results All lesions were resected en bloc without major complications. Histopathology confirmed low-grade adenocarcinomas with deep submucosal invasion, low tumor budding, and no lymphovascular invasion in six cases, and superficial submucosal invasion without high-risk histological features in one case. One pretreated adenocarcinoma showed low-grade T1 morphology with intermediate tumor budding and perineural invasion. One case was a poorly differentiated (G3) T2 carcinoma. Additional findings included tubular adenomas with high-grade dysplasia (n=3), low-grade dysplasia (n=2), one neuroendocrine tumor, and one vascular malformation. Fourteen resections had clear margins. In one D-SMIC case, an R1 deep margin was presumed due to specimen disruption. Subsequent transanal full-thickness resection showed no residual tumor. In one pretreated case, involvement of the deep resection margin resulted in an R1 classification. Conclusion This case series demonstrates that EID is a feasible and promising approach for managing rectal D-SMIC. Further data are needed to refine patient selection and strengthen its role as an organ-preserving alternative to radical surgery.