Sentinel lymph node is the first lymph node in the system of lymphatic drainage of the part of breast that is involved with breast cancer or ductal carcinoma in situ. The first draining lymph node can be identified by various techniques including injection of a blue dye or radioactive material in to the cancer site and following the course of the dye or radioactive substance to identify the first draining lymph node. The surgeon will then determine the pattern of lymphatic flow from the tumor by following the course of the blue dye and the radioactive material. This would lead to identification of the first lymph node into which a tumor drains, and the one that may most likely to contain cancer cells if a lymphatic spread has occurred. Once the sentinel lymph node is identified, this is removed and studied under microscope to determine if that lymph node is involved with breast cancer. If this lymph node is involved with breast cancer, surgeon will do a full exploration of the armpit area and will remove as many
possible lymph nodes as possible. This lymph node exploration surgery may be undertaken at the time of sentinel node biopsy or may be delayed for several weeks after the biopsy. The full lymph node exploration surgery is usually performed under general anesthesia. If the sentinel node is not involved with cancer lymph node exploration is not done thus avoiding various complications associated with the lymph node dissection. This technique of sentinel lymph node biopsy represents a minimally invasive technique for identification of axillary lymph node involvement in patients with ductal carcinoma in situ and invasive breast cancer and is fast replacing the more common axillary lymph node dissection. Not every surgeon can perform the sentinel lymph node biopsy. This is a relatively new procedure and requires substantial expertise on the part of the surgical team. It may take some time for the surgeon to learn and to become an expert in sentinel lymph node biopsy.