The sentinel lymph node mapping in colon cancer.

Malignant tumors of the colon can metastases along the lymphatic system in a sequential way, which means that there will be a first node to be involved and then from this disease will pass to another node and so gradually. The sentinel lymph node is the first lymph node or group of nodes reached by metastasizing cancer cells from a tumor. The present work aims to determine the predictive value of the sentinel lymph node procedure in the staging of non-metastatic colon cancer. In this prospective study joined up only 26 patients with adenocarcinoma of the colon T2-T3, without systemic metastases, and with these criteria for inclusion: a) minimum age: 18 years old; b) staging by total colonoscopy, chest X-ray and CT scan; c) patients classified as ASA 1-3; d) informed consent. Within 20 minutes from the colic resection, the bowel was cut completely along the antimesenteric margin and is performed submucosal injection of vital dye within 5 mm from the lesion at the level of the four cardinal points; then the lymph nodes are placed in formalin and sent to the pathologist. The lymph nodes were subjected to histological examination with haematoxylin-eosin and with the immunohistochemistry technique. From January to December 2008 only 26 patients joined up in this prospective study. From the study were excluded the 4 patients with T4 and M1 tumour. Also 7 patients with stenotic lesions were excluded. Patients considered eligible for our study were only 14. The histopathological examination of haematoxylin-eosin revealed: a) in 4 cases were detected mesocolic lymph node metastases; b) in 10 cases were not detected mesocolic lymph node metastases. In cases there were no metastases, the mesocolic sentinel lymph nodes lymph nodes were examined with immunohistochemical technique; in 2 cases were revealed the presence of micrometastases. In one case was identified aberrant lymphatic drainage patterns (skip metastasis); the sentinel lymph node (negative examination wit eaematoxylin-eosin) was studied with immunohistochemical technique that has not revealed the presence of micrometastases. Examination of the sentinel node is feasible with the ex vivo method. Using the immunohistochemical technique we detect micrometastasis in 20% of the cases, not revealed with the classical haematoxylin-eosin examination. The study of sentinel lymph node with multilevel microsections and immunohistochemical techniques allow a better histopathological staging.