Validation of the Accuracy of Intraoperative Lymphatic Mapping and Sentinel Lymphadenectomy for Early-Stage Melanoma

Abstract

To evaluate the multicenter application of intraoperative lymphatic mapping, sentinel lymphadenectomy, and selective complete lymph node dissection (LM/SL/SCLND) for the management of early-stage melanoma. The multidisciplinary technique of LM/SL/SCLND has been widely adopted, but not validated in a multicenter trial. The authors began the international Multicenter Selective Lymphadenectomy Trial (MSLT) 5 years ago to evaluate the survival of patients with early-stage primary melanoma after wide excision alone versus wide excision plus LM/SL/SCLND. This study examined the accuracy of LM/SL/SCLND in the MSLT, using the experience of the organizing center (John Wayne Cancer Institute [JWCI]) as a standard for comparison. Before entering patients into the randomization phase, each center in the MSLT was required to finish a 30-case learning phase with complete nuclear medicine, pathology, and surgical review. Selection of MSLT patients in the LM/SL/SCLND treatment arm was based on complete pathologic and surgical data. The comparison group of JWCI patients was selected using these criteria: primary cutaneous melanoma having a thickness ≥1 mm with a Clark level ≥III, or a thickness <1 mm with a Clark level ≥IV (MSLT criterion); LM/SL performed between June 1, 1985, and December 30, 1998; and patient not entered in the MSLT. The accuracy of LM/SL/SCLND was determined by comparing the rates of sentinel node (SN) identification and the incidence of SN metastases in the MSLT and JWCI groups. There were 551 patients in the MSLT group and 584 patients in the JWCI group. In both groups, LM performed with blue dye plus a radiocolloid was more successful (99.1%) than LM performed with blue dye alone (95.2%) (p = 0.014). After a center had completed the 30-case learning phase, the success of SN identification in the MSLT group was independent of the center’s case volume or experience in the MSLT. Lymphatic mapping and sentinel lymphadenectomy can be successfully learned and applied in a standardized fashion with high accuracy by centers worldwide. Successful SN identification rates of 97% can be achieved, and the incidence of nodal metastases approaches that of the organizing center. A multidisciplinary approach (surgery, nuclear medicine, and pathology) and a learning phase of ≥30 consecutive cases per center are sufficient for mastery of LM/SL in cutaneous melanoma. Lymphatic mapping performed using blue dye plus radiocolloid is superior to LM using blue dye alone.