Sentinel Lymph Node Biopsy (SLNB) is the diagnostic cornerstone for determining the metastatic spread of cancers like melanoma and breast carcinoma. The procedure identifies the "sentinel" node—the first lymph node to which cancer cells are likely to spread from a primary tumor.

• The Mapping Process: Surgeons inject a radioactive tracer (Technetium-99) or a fluorescent blue dye near the tumor. A handheld gamma detector or infrared camera is then used to track the path of the lymphatic fluid and locate the specific node.

• Clinical Significance: If the sentinel node is negative for cancer, it is highly probable that the rest of the lymph nodes are clear, sparing the patient from a more invasive "axillary dissection," which can lead to complications like lymphedema (permanent limb swelling).

• 2026 Advancements: The use of Superparamagnetic Iron Oxide (SPIO) nanoparticles has replaced traditional dyes in many clinics, offering a non-radioactive, highly visible alternative for intra-operative node identification.