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Session: ePoster: Other Neoplasia and Endoscopy 6 (Mon115)

EP799 - Comparison of local excision and endoscopic mucosal resection for the initial treatment of rectal neuroendocrine tumors

Monday, May 12, 2025
1:31 PM - 1:36 PM PT
Location: Monitor 6, Sails Pavilion, Upper Level

    ePoster Presenter(s)

  • Kyung Su Kim, MD

    Doctor and Researcher
    Division of Colorectal surgery, Department of surgery, Seoul national university hospital
    Seoul, Seoul-t'ukpyolsi, Republic of Korea

    All of the relevant financial relationships listed below have been mitigated.
    This individual has no financial relationships with ineligible companies.

    View ePoster

    • Senior Author(s)

  • SR

    Seung-Bum Ryoo, M.D., Ph.D.

    Professor
    Colorectal Surgery division, Surgery department, Seoul national university hospital
    Seoul, Seoul-t'ukpyolsi, Republic of Korea

    All of the relevant financial relationships listed below have been mitigated.
    This individual has no financial relationships with ineligible companies.

All of the relevant financial relationships listed below have been mitigated.
Kyung Su Kim, MD: This individual has no financial relationships with ineligible companies.
Seung-Bum Ryoo, M.D., Ph.D.: This individual has no financial relationships with ineligible companies.
Purpose/Background: Rectal neuroendocrine tumors (NETs) are increasingly detected due to the widespread use of screening endoscopy. While various studies have compared different techniques of endoscopic mucosal resection (EMR), there is a relative paucity of research comparing EMR with local excision (LE). This study aims to compare EMR and LE as initial treatments for rectal NETs, with a focus on resection margin (RM) involvement and local recurrence through multivariable analysis.

Methods/Interventions: This retrospective, single-center study was conducted at Seoul National University Hospital, including patients diagnosed with rectal NETs from 2004 to 2024. A total of 789 patients were identified, of which 718 underwent EMR and 71 underwent LE. Patients with metastatic disease or carcinoma diagnosed from the initial biopsy were excluded. Primary outcomes included RM involvement, while secondary outcomes comprised local recurrence, time to recurrence (TTR), and complication rates. Multivariable analysis was performed to assess factors associated with RM involvement, and odds ratios (OR) were calculated. Significance was set at p < 0.05.

Results/Outcomes: Among the 789 patients, the basal characteristics were largely comparable between the two groups, although certain distinctions were noted. The mean age was 49.5 ± 11.7 years for the EMR group and 51.8 ± 13.4 years for the LE group (p = 0.119). Tumor size was significantly larger in the LE group (9.9 ± 5.2 mm) compared to the EMR group (6.1 ± 2.8 mm, p < 0.001). Tumor location was closer to the anal verge in the LE group (5.6 ± 2.7 cm) compared to the EMR group (7.2 ± 3.0 cm, p < 0.001).

Although LE showed a higher rate of negative margins compared to EMR (81.7% vs. 73.1%), this difference did not reach statistical significance (p = 0.121). Deep resection margin involvement was significantly less frequent in the LE group (4.2%) compared to the EMR group (13.8%), while local recurrence remained rare in both groups. Only one case of local recurrence was observed in the EMR group, while no local recurrences were noted in the LE group (p = 1.0). Distant recurrence occurred in one case from each group (EMR: 0.1%, LE: 1.4%, p = 0.172). Time to recurrence was recorded as 55 months for local recurrence in the EMR group and 16 months for distant recurrence in both groups. Due to the low number of recurrences, the statistical significance of these comparisons was limited.

Multivariable analysis revealed that LE was associated with a 0.337-fold reduction in the odds of RM involvement compared to EMR (OR: 0.337; 95% CI: 0.142–0.800; p = 0.014). Age was found to be a significant predictor, with patients aged 50 years or older having a 1.825-fold increased risk of RM involvement (OR: 1.825; 95% CI: 1.028–3.239; p = 0.040). Tumor size ≥5 mm was associated with a 2.495-fold increased risk of RM involvement (OR: 2.495; 95% CI: 1.059–5.883; p = 0.037), and tumors located ≤5 cm from the anal verge showed a 2.072-fold increased risk (OR: 2.072; 95% CI: 1.060–4.048; p = 0.033).

Conclusion/Discussion: Local excision (LE) showed superior outcomes in terms of resection margin negativity, particularly with regard to deep resection margin involvement, compared to endoscopic mucosal resection (EMR).

Table 1. Baseline characteristics
Baseline characteristics of patients who underwent EMR and local excision as an initial treatment for rectal neuroendocrine tumors.

Table 2. Outcome s according to initial treatment
Outcomes of patients who underwent EMR and local excision for rectal neuroendocrine tumors.