Sentinel lymph node

Lymph nodes are small organs that play a critical role in the human immune system. Located throughout the body, they filter bodily fluids for harmful substances. The sentinel lymph node is the hypothetical first lymph node (or group of nodes) to which metastasizing cancer cells are likely to spread from the tumor origin site. Identification of the sentinel lymph node(s) following a cancer diagnosis helps assess the extent of metastasis and guide the development of an appropriate treatment plan. The sentinel node procedure (also termed sentinel lymph node biopsy or SLNB) involves identifying, removing, and analyzing the sentinel lymph nodes associated with a particular tumor. In SLNB, a tracer material—often a blue dye or a radioactive substance—is injected near the tumor site. The tracer travels to the first drainage site, allowing the surgeon to locate the sentinel nodes. After identification, the sentinel nodes are removed and sent for laboratory testing to determine the presence of cancer cells.