Extranodal Extension in Colorectal Cancer: Association With Nodal Burden and Disease Recurrence

Background Extranodal extension, defined as tumor invasion beyond the lymph node capsule into perinodal adipose tissue, has been associated with adverse outcomes in several malignancies but is not included in the AJCC-TNM staging system for colorectal cancer. This study evaluated the clinicopathological and prognostic significance of extranodal extension and its extent in lymph node-positive colorectal carcinoma. Methods Sixty-nine patients who underwent curative-intent resection for lymph node-positive colorectal carcinoma were retrospectively analyzed. Patients were classified according to the presence of extranodal extension, and extranodal extension-positive tumors were further categorized as limited (<1 mm) or extensive (≥1 mm). Associations with clinicopathological variables and survival outcomes were analyzed using Cox proportional hazards regression models. Results Extranodal extension was identified in 29 patients (42%) and was associated with a higher metastatic lymph node count, higher N stage, and an increased incidence of distant metastasis (all P < .05). In multivariate analysis adjusted for T stage, N stage, and postoperative adjuvant chemotherapy, extranodal extension remained independently associated with shorter disease-free survival (hazard ratio 2.65; 95% confidence interval 1.10-6.38; P = .031). Extranodal extension was not independently associated with overall survival. Although the extent of extranodal extension correlated with nodal burden, it was not independently associated with survival outcomes. Conclusion Extranodal extension is associated with increased nodal tumor burden and independently predicts shorter disease-free survival in colorectal carcinoma. Routine assessment and reporting of extranodal extension may improve pathological risk stratification.