What is a Sentinel Lymph Node (SNL) Biopsy?

The sentinel lymph node is the first lymph node that filters fluid draining away from a cancerous tumor. If cancer cells are breaking away from the tumor and traveling away from the tumor via the lymph system, the sentinel lymph node is more likely than other lymph nodes to contain cancer.  A sentinel lymph node biopsy (SLN biopsy) is used to:

  • Determine which lymph node or nodes are filtering the tumor area
  • See if any cancer cells have traveled to the node and may be growing there
  • Learn if a more extensive removal of lymph nodes (completion lymph node dissection) is needed.

How does the Sentinel Lymph Node Biopsy Work?

  1. The surgeon injects a special traceable liquid and a blue dye near the tumor site, before or shortly after the tumor is removed.
  2. The surgeon follows the path of the blue dye to find the sentinel lymph node – the first node that filters the lymph draining from the tumor.
  3. The sentinel lymph node is removed and examined under a microscope to check for cancer cells.
  4. If there is no disease in the sentinel lymph node, it is unlikely that the cancer has spread to other lymph nodes.
  5. If cancer is present, other lymph nodes will have to be removed to understand how far the cancer may have traveled.