Focal endoscopic intermuscular dissection in the rectum: feasibility and technical outcomes

Aims The previously described technique of rectal endoscopic intermuscular dissection (EID) involves excising the circular muscle layer beneath the entire lesion [1]. However, deep submucosal invasion or fibrosis does not always affect the entire area in large (≥ 15mm) rectal lesions [2]. This study aimed to evaluate the feasibility, safety and the oncologic radicality (R0) of focal EID for rectal lesions.

Methods A retrospective analysis was performed on prospectively collected data from consecutive rectal lesions resected with focal EID. Indications for EID included suspected deep submucosal invasion or severe submucosal fibrosis (Matsumoto classification F2). Patients were excluded if extramural vascular/nodal invasion or deep T2/T3 cancer was identified on radiological staging. All procedures were performed at a tertiary center for endoscopic resection by a single operator between May and October 2024. Pocket endoscopic submucosal dissection (ESD) was used to detect the muscle retracting sign, indicative of deep submucosal invasion, in lesions without severe fibrosis. In lesions with severe fibrosis, ESD with multipoint traction was employed to identify the target area for focal EID. The deeply invasive or fibrotic area was then isolated using ESD with multipoint traction. Finally, EID was performed circumferentially with a 3 mm margin around the target area to achieve R0 resection.

Results Eight patients (median age 68 years [IQR 64.7-73]; 62.5% male) were included. The median lesion size was 30 mm (IQR 23.75-35.0) with a median distance from the anal verge of 4 cm (IQR 2-5). Lesions were located on the anterior (25%, 2/8) and postero-lateral (75%, 6/8) rectal wall; 87.5%(7/8) were in the distal rectum and 12.5%(1/8) in the proximal rectum. Submucosal fibrosis was absent in 37.5%(3/8) of cases, moderate in 37.5%(3/8) and severe in 25%(2/8). The median procedural time for focal EID was 90.0 minutes (IQR 60.0-113.25), and the median hospital stay was 1 day (IQR 1-1). Technical success was 100%, with a median 71.25% (IQR 57.5-87.5) of the defect area requiring EID. The rates of R0 and curative resection were 100% and 75%, respectively. Histopathology revealed low-grade dysplasia in 25%(2/8), high-grade dysplasia in 12.5%(1/8), T1bSm1 cancer in 12.5%(1/8), T1bSm2-3 cancer in 37.5%(3/8) and T2 cancer in 12.5%(1/8). Intraprocedural complications included bleeding in 50%(4/8) of cases and localized full-thickness perforation in 25%(2/8), with no cases of delayed bleeding or perforation.

Conclusions Focal EID demonstrated feasibility and safety in a real-world setting, achieving high technical success and R0 resection rates for rectal cancer with deep submucosal invasion and severely fibrotic rectal lesions. Focal EID may reduce the need for extensive circular muscular resection in selected cases, potentially decreasing procedural time and complication rates.

Publikationsverlauf

Artikel online veröffentlicht:
27. März 2025

• References

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