Lymph Node Metastases and Tumor Deposits in the Mesorectum Distal to Rectal Cancer: A Need of Total Mesorectal Excision

PURPOSE : Total mesorectal excision has been advocated as the effective operation for patients with rectal cancer to reduce the local recurrence rate after curative resection. Its rationale is to remove possible tumor foci at the mesorectum distal to the level of the rectal cancer. This study was undertaken to clarify the rationale for total mesorectal excision. METHODS : Total mesorectal excision was performed in 72 patients with rectal cancer who admitted in Severance Hospital between December, 1996 and December, 1997. The obtained mesorectums were classified to M0 (from the proximal margin to the distal margin of the tumor), M1 (from the distal margin to 2 cm below the distal margin), M2 (from 2 cm to 5 cm below the distal margin), and microscopic examination was done. RESULTS The nodal metastases were detected in 7 cases and tumor deposits in 4 cases. Especially in M2 with Dukes' C2, the rate of nodal metastases was 3.6 percent and the rate of tumor deposits was 7.1 percent. The nodal metastases and tumor deposits in the distal mesorectum have no correlation with gross finding, size, location and differentiation of the tumor. CONCLUSIONS : En bloc excision of all mesorectal tissue down to at least 5 cm below the lower margin of the tumor is required for patients with advanced rectal cancer to remove possible metastatic lymph nodes and tumor deposits in the distal mesorectum.ope