Clinicopathologic Significance of Extranodal Tumor Extension in Colorectal Adenocarcinoma with Regional Lymph Node Metastasis

Background. This study investigated the clinicopathologic significance of extranodal tumor extension in colorectal adenocarcinoma with lymph node metastasis. Method. Included were 419 patients who underwent curative resection for primary colorectal adenocarcinoma. Results. Extranodal tumor extension was observed more frequently in tumors with ulceroinfiltrative gross type (p = 0.026), higher histologic grade (p = 0.012), high grade tumor budding (p = 0.003), vascular invasion (p < 0.001), perineural invasion (p = 0.015), tumor deposit (p < 0.001), high ratio of metastatic/total lymph nodes (p < 0.001), and high pN stage (p < 0.001). Overall survival was significantly different between an extranodal tumor extension (-) group and an extranodal tumor extension (+) group for both N1 (p = 0.022) and N2 homogeneous staging (p = 0.007). Both overall (p = 0.002) and disease-free survival (p = 0.001) were significantly different between the two groups in an N1a homogeneous group and overall survival was significantly different (p = 0.016) in an N2b homogeneous group. Conclusion. Our study demonstrated that extranodal tumor extension was a useful prognostic factor for colorectal adenocarcinoma with lymph node metastasis, especially in homogeneous pN staging groups.