Sentinel node biopsy: concepts and current status

One of the major routes for spread of cancer is via lymphatic vessels to local lymph nodes. For this reason, local lymph nodes are removed to prevent further spread of tumors. Over the years, surgery has evolved from therapeutic lymphadenectomy for involved nodes to elective lymphadenectomy when the risk of harboring metastasis was high. Two major problems encountered with such an approach included the morbidity of the procedure and a high proportion of nodes being negative on pathologic examination. For these reasons, a new approach has been developed -- Sentinel node biopsy (SNB). SNB is an in vivo assessment of the nodal involvement in early disease. During surgery, the sentinel node is identified by the injection of a blue dye, a radio-colloid substance or both which has been show to have fewer false negatives. This procedure is now standardized during surgery of breast carcinoma or melanoma. However, its use in other types of tumors is still considered investigational at present.