Sentinel lymph nodes in melanoma: necessary as ever for optimal treatment

Lymphatic metastasis is the dominant route of initial spread for most solid tumors. For many such malignancies, including melanomas, surgical treatment previously included removal of all potentially draining regional lymph nodes (elective node dissection). The advent of lymphatic mapping and sentinel lymph node (SLN) biopsy allowed accurate pathologic assessment of the metastatic status of regional nodes and spared patients full dissection if their SLN was clear. In melanoma, recent clinical research has demonstrated that complete lymph node dissection is not clinically beneficial, even for patients with sentinel node metastases and that patients with high-risk primary melanomas benefit from adjuvant systemic immunotherapy, even without nodal disease. These two changes in the standard of care have led to some interest in abandoning surgical nodal staging via the sentinel lymph node biopsy procedure. However, this appears to be premature and potentially detrimental to optimal patient management. The ongoing value of sentinel node biopsy stems from its ability to provide critically important prognostic information as well as durable regional nodal disease control for most patients with nodal metastases, even in the absence of complete dissection of the basin. It also provides an opportunity to identify novel prognostic and predictive immunologic and molecular biomarkers. While it is certainly possible that additional changes in melanoma therapy will make sentinel lymph node biopsy obsolete in the future, at present it remains a minimally invasive, low morbidity means of improving both staging and outcomes.