[Tumors of the lower gastrointestinal tract : Indication and extent of lymph node dissection].

Lymph node dissection is almost always indicated in the treatment of advanced colorectal carcinoma with curative intent. Investigation of at least 12 regional lymph nodes is required for adequate staging. The extent and quality of lymph node dissection influence the long-term prognosis, especially locoregional recurrences and long-term survival. The extent of lymphadenectomy depends on the tumour site and the pattern of potential lymphatic spread following the course of the blood vessels supplying the tumour. Important principles are central ligation of the supplying arteries and draining veins right at their roots, preservation of autonomous nerves at the trunk of the superior mesenteric artery and the aorta and preservation of the integrity of the mesocolon or mesorectum. The number of regional lymph nodes examined as well as the number of lymph nodes with metastases influence the prognosis. Systematic lymph node dissection is also recommended for carcinomas of the small bowel and in most neuroendocrine tumours or carcinomas but is not required for gastro-intestinal stromal tumours.