The Sydney Melanoma Unit experience of sentinel lymphadenectomy for melanoma.

Commenced in 1992, a validation study involving 118 patients who underwent sentinel lymphadenectomy, then immediate complete regional node dissection, confirmed that the histological status of sentinel nodes (SNs) accurately reflects the status of regional nodes. Preoperative lymphoscintigraphy was found to be valuable in determining the number and position of SNs and demonstrated several previously unsuspected lymphatic drainage pathways. The greatest accuracy was achieved by using both blue dye and a gamma probe (to detect radioactivity in SNs after lymphoscintigraphy the previous day). In experience to date, SN positivity has been related to primary tumor thickness (<1.5 mm, 5%; 1.5-3 mm, 14%; >3 mm, 24%). In 827 patients, with a median follow-up of 37 months, recurrence (at any site) has occurred in 47% of SN-positive patients but only 12% of SN-negative patients. Already 30% of SN-positive patients have died of melanoma, but only 6% of SN-negative patients. Although sentinel lymphadenectomy provides accurate staging and important prognostic information, its therapeutic significance has yet to be determined in clinical trials.