Role of lymphatic mapping and sentinel node biopsy in melanoma detection

The approach to the clinically negative regional lymph node basin presents a challenging problem in the clinical management of patients with early-stage melanoma (stage I and II). As a group, stage I and stage II patients generally have a good prognosis following surgical excision of the primary tumour; however, the presence of clinically undetectable nodal disease is an important prognostic factor. Traditionally, these patients are either monitored closely for development of palpable metastases at which time a therapeutic lymphadenectomy would be performed or, have been offered early elective lymphadenectomy that is performed immediately at the time of wide excision of the primary tumour. The high rate of morbidity and lack of proven survival impact for immediate elective lymphadenectomy limit its use. Lymphatic mapping and sentinel node biopsy allow a more selective approach to regional lymph node dissections. Only node-positive patients undergo lymphadenectomy, thereby avoiding the morbidity associated with the procedure for patients without nodal disease. Several studies have confirmed that lymphatic mapping identifies the lymph node most likely to contain disease and confirms the orderly progression of lymphatic metastases. Use of radioactive colloid and a hand-held gamma probe improves the localisation of the sentinel lymph node. Because adjuvant systemic therapy has been proven to prolong survival in patients with nodal involvement, lymphatic mapping and sentinel node biopsy, by identifying patients with clinically negative, but pathologically positive disease, may improve their outcome.