Study on the No.253 Lymph Node Metastasis Patterns in Left-Sided Colon and Rectal Cancer

The No. 253 lymph node (also named as apical lymph node of inferior mesenteric artery), as the third station in the inferior mesenteric artery lymphatic system, plays a vital role in the lymphatic circulation of the descending colon, sigmoid colon, and rectum. They serve as the last barrier for tumor metastasis from regional to distant sites. The definition of the range of the No.253 lymph node primarily follows the Japanese Colorectal Cancer Treatment Guidelines: the medial boundary is the segment from the root of the inferior mesenteric artery to the origin of the left colic artery, the caudal boundary is from the origin of the left colic artery to the intersection with the inferior mesenteric vein, the lateral boundary is the outer margin of the inferior mesenteric vein, and the cranial boundary is from the horizontal section of the duodenum to the beginning of the jejunum. However, the pattern of metastasis of the No.253 lymph node in colorectal cancer remains unclear, with most studies being retrospective and showing significant differences in results. Therefore, the investigator plans to be the first internationally to carry out this retrospective, registry-based study to determine the metastasis pattern to the No. 253 lymph node in colorectal cancer. This will provide definitive clinical evidence for D3 lymph node dissection in colorectal surgery.