More accurate staging and a lower rate of postoperative complications are the main reasons for having a sentinel lymph node biopsy. Nodal status (positive for melanoma spread or negative for no melanoma spread) is the most significant predictor of disease-free survival. Prompt staging leads to earlier treatment.
Studies have shown that only 20% of melanoma patients with a Breslow thickness between 1.5 - 4 mm have metastasis in their sentinel node. This is the 20% that will require removal of all lymph nodes in the drainage basin surrounding a primary melanoma. The procedure carries a higher complication rate (swelling in arms and legs, wound necrosis, infection) and is unnecessary in the majority of melanoma patients.
Finally, errors during pathology testing (approximately 12% of lymph nodes in the conventional routine) can be decreased if a single (sentinel) node is tested in a detailed manner rather than testing the standard few nodal sections in a higher number of lymph nodes per patient.