What is sentinel lymph mapping?

Sentinel node mapping is used to sample the lymph nodes most likely to be involved with a particular cancer. Instead of doing a much more invasive procedure that removes 15 to 20 nodes, only 1 or 2 specific nodes can be removed to get the same information. A radioactive protein is injected in the area of the cancer and a special Geiger counter is used to fine the targeted nodes. These nodes are then examined by a pathologist to determine if the cancer has spread.