lymph node mapping

Since tumor cells can spread through the lymphatic system, it is necessary to check whether the sentinel lymph node (the first lymph node in the lymphatic system to which the tumor drains) is infected with cancer cells. The sentinel lymph node is identified by injecting a radioactive substance or a dye solution (or both) into the tumor and then testing which lymph node is the first to contain the dye or the radioactive substance. The gland is removed and tested for the presence of cancer cells. If the gland is clean from cancer cellss, it is assumed that the rest of the lymph nodes are clean and need not be removed.