EP258 - Evaluating the Oncologic Outcomes and Feasibility of IMA High Ligation for Central Lymph Node Dissection in Sigmoid Colon Cancer

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Purpose/Background: The impact of central lymph node metastasis (CLNM) on oncologic outcomes in colon cancer has been a subject of interest among surgeons. Central lymph node metastasis has gathered increasing attention due to its potential impact on oncologic outcomes. Emerging evidence suggests that central node involvement may reflect a more aggressive disease phenotype, making dissection of central nodes critical for better tumor staging, underscoring the need for further investigation into its prognostic value. This study aims to evaluate the oncologic outcomes of central lymph node metastasis. From this we can identify preoperative factors that increase the likelihood of CLNM, assess the postoperative complications associated with such lymph node dissection and together, we can optimize the surgical decision-making, ensuring that the benefits of this complex approach are realized in patients most likely to achieve significant oncologic benefits while minimizing potential complications.

Methods/Interventions: Retrospective analysis was conducted on 995 sigmoid colon cancer patients who underwent laparoscopic low anterior resection (LAR) or anterior resection (AR) and CLND with IMA high ligation between 2013~2023. Patients were categorized based on lymph node metastasis extent: no metastasis (n=599), peritumoral/pericolic metastasis (n=352), and central metastasis (n=44). Clinicopathologic factors, tumor characteristics were recorded and CLNM was confirmed via histopathological examination. Oncologic outcomes, including overall survival (OS), disease-free survival (DFS) were analyzed in relation to lymph node metastasis location.

Results/Outcomes: 4 (4.4%) had CLNM. Median follow-up period was 47.9 (0.3-131.7) months. 5-year OS rates were 99.7% for no metastasis, 87.0% for peritumoral/pericolic metastasis, and 79.7% for central metastasis (p=0.002). 5-year DFS rates were 97.8% for no metastasis, 90.9% for peritumoral/pericolic metastasis, and 85.1% for central metastasis (p < 0.001). Multivariate analysis identified CLNM as a predictor of poor OS (HR 2.6, 95% CI 1.1-6.2, p=0.029) and DFS (HR 2.6, 95% CI 1.2-5.3, p=0.011). Presence of pathologic lymphatic invasion was associated with significantly worse DFS (HR 1.6, 95% CI 1.1-2.4, p=0.018). A total number of 165 out of 995 patients were reported to have complications, making our total complication rate 17%. Out of the 165 patients, only 7% had a clavien dindo grade higher than 3 and required a more aggressive intervention.

Conclusion/Discussion: CLNM in sigmoid colon cancer patients is associated with significantly worse oncologic outcomes. Higher rates of CLNM were found in patients with preoperative CEA values>5; higher clinical T, N stage; and poorly differentiated adenocarcinomas. Furthermore, the complication rate of IMA high ligation was relatively low. Doctors who are not yet proficient in low ligation and central node dissection, performing IMA high ligation can be more advantageous, especially in groups with the aforementioned clinical factors. These findings underscore the importance of meticulous surgical techniques and the potential need for tailored surgery to improve survival outcomes in this subset of patients.