Sentinel lymph node 3123632 219362679 2008-06-14T21:38:37Z Lightbot 7178666 Units/dates/other The '''sentinel lymph node''' is the hypothetical first [[lymph node]] or group of nodes reached by [[metastasis|metastasizing]] [[cancer]] [[cell (biology)|cell]]s from a [[tumor]]. ==Physiology== The spread of some forms of cancer usually follows an orderly progression, spreading first to regional lymph nodes, then the next echelon of lymph nodes, and so on, since the flow of [[lymph]] is unidirectional. ==Uses== The concept of the sentinel lymph node is important because of the advent of the '''sentinel lymph node biopsy''' technique, also known as a '''sentinel node procedure'''. This technique is used in the [[cancer staging|staging]] of certain types of cancer to see if they have spread to any lymph nodes, since lymph node metastasis is one of the most important [[prognosis|prognostic signs]]. [[Image:Sentinel lymph node (axilla).jpg|thumb|A blue stained sentinel lymph node in the [[axilla]].]]To perform a sentinel lymph node [[biopsy]], the physician performs a lymphoscintigraphy, wherein he/she injects a harmless [[radionuclide|radioactive substance]] near the tumor. This is usually done several hours before the actual biopsy. About 15 min before the biopsy he/she injects a blue dye in the same manner. Then, during the biopsy, the physician visually inspects the lymph nodes for staining and uses a [[Geiger counter]] to assess which lymph nodes have taken up the radionuclide. One or several nodes may take up the dye and radioactive tracer, and these nodes are designated the ''sentinel lymph nodes''. The physician then removes these lymph nodes and sends them to a [[pathologist]] for rapid examination under a [[microscope]] to look for the presence of cancer. A [[frozen section procedure]] is commonly employed (which takes 20-30 minutes), so if neoplasia is detected in the lymph node a further [[lymph node dissection]] may be performed. With malignant melanoma, many pathologists eschew frozen sections for more accurate "permanent" specimen preparation due to the increased instances of false-negative with melanocytic staining. There are various advantages to the sentinel node procedure. First and foremost, it decreases unnecessary lymph node dissections where this is not necessary, thereby reducing the risk of [[lymphedema]], a common complication of this procedure. Increased attention on the node(s) identified to most likely contain metastasis is also more likely to detect micro-metastasis and result in staging and treatment changes. The main uses are in [[breast cancer]] and [[malignant melanoma]] [[surgery]], although it has been used in other tumor types ([[colon cancer]]) with a degree of success.<ref>Tanis PJ, Boom RP, Koops HS, Faneyte IF, Peterse JL, Nieweg OE, Rutgers EJ, Tiebosch AT, Kroon BB (2001a). Frozen section investigation of the sentinel node in malignant melanoma and breast cancer. ''Ann Surg Oncol'' 8:222-6. PMID 11314938.</ref> However, the technique is not without drawbacks, particularly when used for melanoma patients. Failure to detect cancer cells in the sentinel node can lead to a false negative result - there may still be cancerous cells in the lymph node basin. In addition, there is no compelling evidence that patients who have a full lymph node dissection as a result of a positive sentinel lymph node result have improved survival compared to those who do not have a full dissection until later in their disease, when the lymph nodes can be felt by a physician. Such patients may be having an unnecessary full dissection, with the attendant risk of [[lymphedema]].<ref>Thomas J (2008). Prognostic false-positivity of the sentinel node in melanoma. ''Nat Clin Pract Oncol.'' 5(1):18-23. PMID 18097453.</ref> The sentinel node procedure in breast cancer was pioneered by surgical oncologist, Armando Giuliano, MD at the [[John Wayne Cancer Institute]] in the 1990s, and confirmative trials followed soon after.<ref>Tanis PJ, Nieweg OE, Valdes Olmos RA, Th Rutgers EJ, Kroon BB (2001b). History of sentinel node and validation of the technique. ''Breast Cancer Res'' 3:109-12. PMID 11250756.</ref> ==References== {{reflist}} {{Lymphatic system}} [[Category:Lymphatic system]] [[Category:Oncology]] [[da:Skildvagtslymfekirtel]] [[de:Wächterlymphknoten]] [[nl:Schildwachtklier]] [[sk:Sentinelová uzlina]]