Re-examining distal resection in colon cancer

Background: In colon cancer, data regarding proximal and distal metastasis to lymph nodes remains scarce. Objectives: To evaluate lymph node distribution along the longitudinal axis of the colon as related to a tumor to reexamine the common practice of 5 cm proximal and 2 cm distal resection margins. Methods: We studied 106 patients (53 males and 53 females, mean age 67.9 ± 10 years) who had undergone left hemicolectomy or sigmoidectomy. Colonic cancer specimens were divided into five zones proximally and distally to the tumor. For each zone, overall lymph node evaluation and ratio was performed. Results: The mean number of retrieved lymph nodes per patient was 24.3 ± 12, with 54.9% of the nodes concentrated in zone I, 22.1% in zone II, 9.5% in zone III, 10.3% in zone IV, and 3% in zone V. While most positive nodes were found in zone I, significant numbers were also detected in both directions proximally and distally to the tumor. Conclusions: It seems that longer colonic segments proximally, and especially distally, should be considered for resection to significantly reduce the chances of finding involved lymph node.