Lymphadenectomy or lymph node dissection is the surgical removal of one or more groups of lymph nodes. It is almost always performed as part of the surgical management of cancer. In a regional lymph node dissection, some of the lymph nodes in the tumor area are removed; in a radical lymph node dissection, most or all of the lymph nodes in the tumor area are removed.
More recently, the concept of sentinel lymph node mapping has been popularized by Donald Morton and others. Cancer with various primary sites (breast, melanoma, colorectal, etc.) often metastasize early to the first drainage lymphatic basin. This process is predictable anatomically according to the primary site in the organ and the lymphatic channels. The first nodes (sentinel nodes) can be identified by particulate markers such as lymphazurin, methylene blue, India ink and radio-labelled colloid protein particles injected near the tumor site. The draining sentinel node can then be found by the surgeon and excised for verification by the pathologist if tumor cells are present, and often these tumor cells are few and only easily recognized by careful examination or by using techniques such as special stains, i.e. immunohistochemical. When the sentinel node is free of tumor cells, this is highly predictive of freedom from metastasis in the entire lymphatic basin, thus leading to futility of a full node dissection.
The practice of sentinel lymph node mapping has changed the surgical approach in many cancer systems, sparing a formal lymph node dissection for patients with sentinel lymph node negative for tumor and directing a full node dissection for patients with sentinel lymph node positive for tumor metastases. For example in stage II breast carcinoma, using the sentinel lymph node technique, 65% of patients could be spared from a formal node dissection.
Lymphedema may result from lymphadenectomy. Extensive resection of lymphatic tissue can lead to the formation of a lymphocele.