What is Sentinel Lymph Node Biopsy?

Sentinel lymph node biopsy is a diagnostic procedure used to determine whether breast cancer has spread to axillary lymph nodes (lymph glands under the arm). The surgeon finds and removes the sentinel (first) lymph node (generally one to three nodes) that receives drainage from the breast. The pathologist then examines it for cancer cells. If the sentinel nodes do not contain tumor (cancer) cells, this may eliminate the need to remove additional lymph nodes under the arm.

How is Sentinel Lymph Node Biopsy Performed?

To identify the sentinel lymph node, the surgeon injects a dye and/or a radioactive tracer into the area around the person's primary breast tumor. The dye or tracer will travel to the lymph nodes, arriving at the sentinel node first. The surgeon can find the node when it turns color (if the dye is used) or emits radiation (if the tracer is used).

Sentinel lymph node biopsy has a lower risk of lymphedema (swelling of the arm) than axillary lymph node dissection, which removes most of the lymph nodes from under the arm. If the sentinel node is cancer-free, research has shown that there is a good possibility that the subsequent nodes will also be free of cancer and no further surgery of the lymph nodes is performed. If the sentinel lymph node shows cancer is present, then the surgeon will perform an axillary lymph node dissection.

Axillary lymph node dissection involves the surgeon removing lymph nodes from under the arm and having them examined by a pathologist for cancer cells. Because each person has different number of underarm lymph nodes, the actual number of lymphnodes removed varies from four to 60.