Distribution of lymph node metastasis and level of inferior mesenteric artery ligation in colorectal cancer

To investigate the distribution of lymph node metastasis along the inferior mesenteric artery (IMA) and clarify whether high ligation of the IMA is important or not, we examined the surgical results of 172 patients with cancer of the sigmoid colon and rectum. Histologically, lymph node metastasis was absent in 108 (63%) patients and present in 64 (37%) patients. The distribution was adjacent to the wall of the rectum (35.5%) and sigmoid colon (10.5%), along the IMA (7.7%) and sigmoid colic artery (6.3%), and at the root of the IMA (0.7%, 1 of 135 patients). The presence of lymph node metastasis was predicted by the operative findings of lymph node metastasis (p < 0.01) and serosal invasion (p < 0.05) and by the histologic type of tumor (p < 0.05). These results indicate that lymph node metastasis at the root of the IMA is rare, and complete removal of the pericolic and intermediate nodes (D2 dissection) without high ligation of the IMA is feasible for cancer of the sigmoid colon and rectum.