BACKGROUND: Endoscopic submucosal dissection (ESD) of colorectal lesions is technically demanding and carries a significant rate of noncurative resection. There is limited data describing clinical outcomes for patients with noncurative ESD for benign and malignant colorectal lesions and subsequent management are variable. We aimed to assess the outcomes after non-curative ESD of colorectal lesions.
METHODS: This is a multicenter retrospective analysis of consecutive patients who underwent colorectal ESD for superficial epithelial colorectal neoplasms from 2016 to 2023 from 12 centers (8 US, 2 Canada, 1 Brazil, 1 UK). We included lesions which were non-curative and had clinical follow up. Noncurative resection was defined as noninvasive (adenomas, HGD or intramucosal cancer) with piecemeal resection (group 1); noninvasive lesions after en bloc resection with lateral margin positivity on pathology (group 2), or submucosal invasive cancer (SMC) resected piecemeal (group 3) or en bloc, at least one of poor prognostic features [LV invasion, poor differentiation, deep or lateral margin positivity, tumor budding or >1000 um SM involvement] (group 4). We evaluated the rate of local recurrence, residual lesion at the colonic wall on the surgical specimens, LN and distant metastasis, and mortality.
RESULTS: Of 1994 colorectal ESD cases, 189 (9.5%) were noncurative. Of these, 79 (41.8%) lesions were non-invasive, and 110 (58.2%) were SMC (Table 1). There were 35 (18.5%) lesions in group 1, 43 (22.8%) in group 2, 15 (7.9%) in group 3, and 96 (50.8%) in group 4. In non-invasive group with follow-up data (n=69), median follow-up time of 52.5 weeks (IQR 31-99), local recurrence was identified in 1 (1.4%) patient: 1 (2.9%) in group 1 vs 0 in group 2. No cases developed metastasis or died from colon cancer. In SMC group with follow-up data (n=77), 62 patients underwent surgery: 9 (14.5%) with residual tumor in the wall and 12 (19.4%) with lymph node positivity. 15 patients did not undergo surgery were monitored with median follow-up time of 47 weeks (IQR 24-100). Local recurrence and LN/distal metastasis were found in 1(6.7%) and 0(0%), respectively. Overall, local recurrence/ residual lesion at the wall was found in 13% and LN/distal metastasis was noted 15.6% in the SMC group. Mortality rate was 2.1% and the colon cancer-specific mortality was 1.1% (Table 2).
CONCLUSIONS: We found very low rates of local recurrence after noncurative en bloc ESD for benign lesions with lateral margin positivity on pathology (0%). A surveillance colonoscopy at 3-6 months in these patients, as suggested by society guidelines may not be necessary and the first surveillance could be postponed to at least 12 months. SMCs after non-curative ESD have a higher risk of residual lesions (13%) and metastasis (15%). Surgical resection is recommended in surgically fit patients.

Table 1. Patient and Procedure Characteristics

Table 2. Procedural Outcomes

Aihara Hiroyuki

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