Sentinel lymph node mapping has already been accepted as part of the treatment for malignant melanomas of the skin and in breast carcinomas. The status of lymph nodes is an important prognostic marker in colorectal carcinoma as well. The authors tried the feasibility of this technique in colorectal carcinomas. The technique is analogous to the one used in breast cancer and melanoma: 2 ml of 2.5% Patentblau dye was given subserosally around the tumor. After resection the specimen was immediately sent to pathology where the lymph nodes were removed. This technique has been tried on 31 patients, 22 with colonic and 9 with rectal tumors. Of these patients, 15 were Dukes stage C, 14 were Dukes stage B and 2 were Dukes stage A. An average 4.3 blue lymph nodes were found in colon tumors and 5.4 in rectal tumors and an average 14 unstained lymph nodes were found in colon tumors, and 7 in rectal tumors. The blue nodes were predictive of the nodal status in 9 of the 15 Dukes stage C patients. In these cases the blue lymph nodes contained metastases and there were 2 cases where metastases were limited to the blue lymph nodes.
Summary: The authors found a high false negative rate for lymphatic mapping with the vital dye technique, therefore they try to change the method according to that used by Saha et al. The aim of sentinel node identification in colorectal carcinomas would be improved staging rather than reducing of the extent of lymphadenectomy. The role of lymphatic mapping in large bowel cancers needs further investigations. Until the results are reliable, as many lymph nodes as possible have to be excited and sent for histology.