A Sentinel Lymph Node is the first lymph node that receives drainage from a tumor. It plays a crucial role in the staging of cancer, as it helps determine whether cancer has spread beyond the primary site. If cancer cells are found in the sentinel lymph node, it may indicate that the disease has begun to spread to other parts of the body. During a procedure called Sentinel Lymph Node Biopsy, a dye or radioactive substance is injected near the tumor to identify the sentinel lymph node. This minimally invasive technique allows doctors to assess the presence of cancer without removing multiple lymph nodes, reducing potential complications and recovery time.