Sentinel Lymph Node Biopsy
A sentinel lymph node is the first node in a group of lymph nodes in the body where cancer cells may move to after they have left the original cancer site and started to spread. By pinpointing the first few lymph nodes into which a tumor drains, a sentinel lymph node biopsy (SLNB) procedure identifies, removes, and examines the lymph nodes to determine whether cancer cells are present. This procedure helps doctors remove only those nodes most likely to contain cancer cells because the sentinel nodes are the first place that cancer is likely to spread.
To locate the sentinel nodes, a surgeon injects a radioactive substance, a blue dye, or both near the tumor to locate the position of the sentinel lymph node. The surgeon then uses a device that detects radioactivity to find the sentinel node or looks for lymph nodes that are stained with the blue dye. Once the sentinel lymph node is located, the surgeon makes a small incision and removes the node.
A pathologist examines the sentinel nodes for the presence of cancer cells. If cancer is found, the surgeon may remove additional lymph nodes, either during the same biopsy procedure or during a follow-up surgical procedure.
In addition to helping doctors stage cancers and estimate the risk that tumor cells have developed the ability to spread to other parts of the body, SLNB may help some patients avoid more extensive lymph node surgery. Removing additional nearby lymph nodes to look for cancer cells may not be necessary if the sentinel node is negative for cancer. If fewer lymph nodes are removed, some of the adverse effects common during surgery may be reduced or avoided.
National Cancer Institute: Sentinel Lymph Node Biopsy http://www.cancer.gov/about-cancer/diagnosis-staging/staging/sentinel-node-biopsy-fact-sheet. Accessed 15July2015.