The status of the regional lymphatic basin in patients with malignant melanoma remains the most powerful predictor of recurrence and survival. Lymphatic mapping and sentinel lymph node (SLN) biopsy has become the standard of the nodal staging due to lower patient morbidities and more accurate staging. Investigations have determined the following:
1. The nodal staging system for melanoma depends on the number of nodes positive so that patients with 1 node positive do better than patients with 2-3 nodes positive, do better than patients with 4 or more nodes positive. Examining the distribution of nodal metastases in the regional basin has determined that patients with metastatic disease confined to the SLNs have a much better survival compared to patients with SLN and Non-SLN metastases.
2. The SLN status plays a major role in conditional survival estimates for patients with melanoma. This analysis shows that if patients live 4 years from their diagnosis without a recurrence, then survival becomes equal no matter what stage of disease the patients were assigned at the time of diagnosis. However at no time do they achieve the same survival as the normal population.
3. Gene expression assays have been developed for the early stage melanoma population. A 31-gene panel can divide patients into 2 groups, either at high risk or low risk for recurrence. This data has been used in combination with the SLN status to determine prognosis and influence surgical care. Patients have been identified who are SLN negative but have the Class II signature for high risk for recurrence. These patients have similar survivals as the microscopic Stage III population staged with SLN biopsy and may in turn be candidates for CLND or adjuvant therapies.
4. Recent data from Germany has suggested that in the positive SLN population, patients may not need a complete regional node dissection. This finding needs to be confirmed before guidelines are changed.
Nodal staging for patients with melanoma using the sentinel lymph node procedure remains the standard of care for patients with melanoma. More recent studies have highlighted the importance of non-SLN metastases, more meaningful condition survival prognostic information, a gene profile assay that compliments the lymphatic mapping procedure, and an observation alternative for patients with a positive SLN.