A procedure in which a dye and/or radioactive substance is injected near the cancer. The dye or radioactive substance flows into the lymph nodes. The first lymph node that it reaches is called the sentinel lymph node. It is also the first lymph node that cancer cells might spread to after breaking away from the main cancer in the breast. Sometimes there is more than one sentinel node. A surgeon finds the sentinel lymph node, or nodes, by looking for the dye or detecting the radioactive substance. Then the node or nodes are removed and checked to see if there are cancer cells in them.
Read about sentinel lymph node dissection.
Audio contributed by: Thora Birch