Progressive Disease in Sentinel-negative Melanoma Patients: Biological Differences and Importance of Sentinel Lymph Node Biopsy.

Abstract

Among the most important prognostic factors in melanoma is the sentinel lymph node (SLN) status. Using our electronic database we identified 109 of 890 SLN-negative patients with progressive disease (PD). These patients were characterized for melanoma type, molecular type, sequence and extent of metastatic spread. A total of 61 of 109 SLN-negative patients had PD in the SLN-basin indicating false-negative SLN (group-1). Forty eight of 109 patients had PD at distant sites and were therefore impossible to be identified using SLN biopsy (group-2). Despite distant spread these patients had significantly more single organ metastasis (p<0.001) and significantly longer disease-free-survival (p=0.001) compared to group-1. Additionally, to significant differences on a molecular basis between the two groups (p=0.01), all lentigo maligna and spindle-cell-melanomas belonged to group-2 and all, except one lentigo maligna melanoma, had single visceral metastasis. Two different biological groups among SLN-negative patients with PD were demonstrated. Extravascular-migratory-metastasis, rather than hematogenous spread, might be responsible for the observed PD with single organ involvement.