From the Editors

In the evolution of melanoma care, it has repeatedly been demonstrated that less can be more. Once, at first sight of a primary tumor, entire limbs were sacrificed to prevent metastasis. Not long ago, 3-5-cm margins around the primary were standard in surgical excision, whereas now 1-cm margins are routine. And just a generation ago, primaries deemed high-risk most often led to complete elective regional lymph node dissection (ELND). This practice ended with the gradual acceptance of sentinel lymph node biopsy (SLNB), the now standard tissue-sparing surgical technique developed by Dr. Donald Morton in the early 1990s. However, the role of SLNB in clinical practice continues to be debated.

SLNB was designed to release surgeons from the difficult choice between simple observation (“watch and wait”) and ELND by allowing removal of just one or two nodes from the lymph node basin closest to a primary tumor to determine if metastases have reached the basin. It has eliminated considerable morbidity for numerous melanoma patients who formerly might have undergone ELND but proved to have negative sentinel nodes, and has allowed more precise staging to inform therapeutic decisions and improve stratification for clinical trials. However, SLNB for melanoma has remained controversial, with some critics arguing against its therapeutic value in the absence of definitive evidence that it improves survival, and others even questioning its value as a staging tool.

Unfortunately, the controversies were not resolved with the publication in 2014 of Morton, et al’s long-awaited Multicenter Selective Lymphadenectomy Trial-1 (MSLT-1), the longest, largest study of SLNB and LND ever undertaken. The results were mixed, with a negative result for the primary analysis of the effect on overall survival and a positive finding for a variably interpreted secondary analysis confined to a subset of patients with regional metastases. The controversy is compounded by disagreement on the role of completion LND in patients with positive sentinel nodes. Preliminary data from a recent German study provide an initial answer to the question, and Morton, et al’s follow-up study, the pending MSLT-2 analysis, is exploring the issue in a much greater number of patients.

Our lead story in this issue of The Melanoma Letter, by Drs. Charles Balch, Mark Faries, and John Thompson, presents an authoritative and detailed review of SLNB in melanoma, with special attention to the results of MSLT-1. Our second story, by Dr. Jean-Jacques Grob, explores the questions remaining about the efficacy of SLNB, reviews the German data on completion LND, and looks forward to an era of increasingly precise staging/prognostication based on molecular studies of the primary tumors and blood. These two complementary stories provide a fairly comprehensive update and perspective on this important subject.

Dr. Morton died in 2014 before MSLT-1 could be published, but not before his brilliantly conceived and researched technique came to be considered a vital staple of melanoma staging and treatment, especially for patients with tumors of intermediate thickness, who were considered (and subsequently proven by MSLT-I) to be the group most likely to benefit from SLNB. Whatever the ultimate fate of the technique, it was a milestone achievement in the evolution of the field. 

Allan C. Halpern, MD • Editor-in-Chief       

Ashfaq A. Marghoob, MD • Associate Editor