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Sentinel Node Biopsy (Selective Lymphadenopathy) What is a sentinel node and how is it found? When cancer begins to spread, malignant cells enter tiny vessels called lymphatics, which carry the cells to a group of nearby lymph nodes. In breast cancer these are typically the lymph nodes in the armpit (axilla). In traditional breast cancer surgery, most of the lymph node groups in the axilla are removed by the surgeon and examined by the pathologist for cancer cells. This surgery does not count the total number of lymph nodes at the time of surgery. Rather, it removes a packet of tissue that is outlined by muscle and blood vessel structures. A sentinel node is the first lymph node to which cancer will spread. In usual surgical practice, doctors do not know which node this will be. Using special techniques and new technology, we now have a good chance of identifying the first or sentinel node(s) to which cancer cells will travel. The technique for identifying this node or nodes can involve utilizing blue dye alone or blue dye and a radioactive material (radioisotope). The material (s) of choice is injected into the area under the nipple, or sometimes around the tumor, less often into the skin. The dye and or radioisotope travel to the regional node system. This is aided by a timed massage of the breast tissue several minutes before an incision is made in the armpit area. If radioisotope is used, sometimes it is injected many hours before surgery and a preoperative “map” is made in nuclear medicine using a gamma camera to map out lymphatic flow. This is called preoperative lymphoscintigraphy. During surgery, a small hand held “counter” is used by the surgeon to identify lymph nodes which show high counts of the radioactive material, or are “hot”. The blue dye is a visual aid to find sentinel lymph nodes. This dye stains the tiny lymphatic vessels blue. They are then visually followed to find blue stained sentinel lymph nodes, which are removed one at a time. WHAT IS THE ADVANTAGE OF SENTINEL LYMPH NODE BIOPSY? In traditional breast cancer surgery, most of the lymph nodes in the axilla are removed. When done by a skilled surgeon, and the patient is well instructed in how to care for their arm, there is a relatively low risk of serious complications. Nevertheless, there is a chance of persistent swelling of the arm (lymphedema). In theory, if doctors can identify the sentinel node(s) and it does not contain cancer cells, then the remaining nodes in the axilla should be negative as well and need not be removed. However, if the sentinel node reveals spread of cancer cells, then the other nodes may also contain cancer and should be removed. This is now called a “completion axillary lymph node dissection”. Sometimes the sentinel lymph node cannot be identified. This may be due to prior surgery causing too much change in the lymphatic connections between breast and axilla, or if the node is entirely replaced by tumor. If the surgeon cannot satisfactorily identify the sentinel node(s), a standard completion lymph node dissection is performed. OTHER CONSIDERATIONS Breast cancer treatment recommendations are made using many pieces of information including the tumor size and location, breast size, menopausal status, associated medical conditions, cancer grade as determined under the microscope, and biological features of the cancer, determined by other special techniques. The technique of sentinel lymph node biopsy for breast cancer is appropriate for many if not most breast cancer patients. It is best performed after special training and with experience in the technique. There is a small but real (2 to 5%) incidence of allergy to the blue dye. This usually shows up during the operation or recovery room and is treated according to its severity: mild, moderate or severe. There is no known predictor of allergy to the dye. The pathologist, using a special technique called “cytoprep scrape”, does evaluation of the sentinel lymph node. It is around 90% accurate, but full determination of the lymph node is completed a day or two after surgery, when the nodes are fixed with H&E (the normal way to read surgical pathology slides), and also with special stains called immunoperoxidase stains. Rarely the sentinel lymph node is “clear” in the operating room and “positive” by the other stains. Special classifications have been created to study these circumstances. It is not known whether lymph nodes “positive” only by immunoperoxidase stains have the same significance as being noted by the traditional H & E stain. Chemotherapy is almost always recommended for patients if their tumor is found in lymph nodes. If four or more lymph nodes are positive, additional treatment alterations may be discussed. Back to the Articles, Information, and Self Examination section. |