Identification, Clinical Significance, and Management of Very Small Melanoma Metastases in Sentinel Lymph Nodes

Excerpt

Early treatment of metastatic melanoma remains appealing. In the 1980s Morton et al. evaluated whether they could identify, without complete lymphadenectomy, the individual regional nodes most susceptible to early metastases.1 These studies developed S-100 protein as the first immunohistochemical marker for melanocyte-derived cells,2,3 established that preoperative lymphoscintigraphy identified the regional lymph nodes that received lymph from the site of a primary melanoma, and that intradermally injected marker dyes identified the actual lymph node(s) [sentinel nodes (SNs)] that received lymph from a primary melanoma.1 Animal studies demonstrated the predictability and reliability of lymph drainage from specific anatomical sites.4 These techniques were applied to melanoma patients. After identification by isotope and marker dye, the SN was evaluated for melanoma. Complete lymphadenectomy (completion lymphadenectomy) was then performed and the non-SNs (NSNs) were evaluated for metastases. In most patients, metastases were exclusive to the SNs; in a small minority, tumor was present in one or more NSNs. Patients with tumor-negative SNs very rarely had tumor in NSNs. These extended studies were the basis of our initial report regarding the novel techniques of lymphatic mapping and SN biopsy.1 A multicenter trial [Multicenter Selective Lymphadenectomy Trial 1 (MSLT-1)] was initiated to compare wide excision followed by observation with wide excision/lymphatic mapping and SN biopsy, with immediate completion lymphadenectomy if the SN contained tumor. The final results of MSLT-1 (with 10-year survival data) were published in 2014.5 These approaches are widely used in melanoma management and have been adapted to the treatment of breast cancer and other cancers. …