The Prognostic Significance of Sentinel Lymph Node Status for Patients with Thick Melanoma.

BACKGROUND: Sentinel lymph node biopsy (SLNB) is recommended for patients with intermediate-thickness melanoma, but the use of SLNB for patients with thick melanoma is debated. This report presents a single-institution study investigating factors predictive of sentinel lymph node (SLN) metastasis and outcome for thick-melanoma patients . METHODS: A retrospective review of a single-institution database from 1997 to 2012 identified 147 patients with thick primary cutaneous melanoma (≥4 mm) who had an SLNB. Clinicopathologic characteristics were correlated with nodal status and outcome. RESULTS: The median age of the patients was 67 years, and 61.9 % of the patients were men. The median tumor thickness was 5.5 mm, and 54 patients (36.7 %) had a positive SLN. Multivariable analysis showed that only tumor thickness significantly predicted SLN metastasis (odds ratio 1.14; 95 % confidence interval (CI) 1.02-1.28; P = 0.02). The overall median follow-up period was 34.6 months. Overall survival (OS) and melanoma-specific survival (MSS) were significantly worse for the positive versus negative-SLN patients. Multivariable analysis showed that age [hazard ratio (HR) 1.04; 95 % CI 1.01-1.07; P = 0.02] and SLN status (HR 2.24; 95 % CI 1.03-4.88; P = 0.04) significantly predicted OS, whereas only SLN status (HR 3.85; 95 % CI 2.13-6.97; P < 0.01) significantly predicted MSS. CONCLUSIONS: Tumor thickness predicts SLN status in thick melanomas. Furthermore, SLN status is prognostic for OS and MSS in thick-melanoma patients, with positive-SLN patients having significantly worse OS and MSS. These findings show that SLNB should be recommended for thick-melanoma patients, particularly because detection of SLN metastasis can identify patients for potential systemic therapy and treatment of nodal disease at a microscopic stage.

Activated Wnt/beta-catenin signaling in melanoma is associated with decreased proliferation in patient tumors and a murine melanoma model.

This study demonstrates that in malignant melanoma, elevated levels of nuclear beta-catenin in both primary tumors and metastases correlate with reduced expression of a marker of proliferation and with improved survival, in contrast to colorectal cancer. The reduction in proliferation observed in vivo is recapitulated in B16 murine melanoma cells and in human melanoma cell lines cultured in vitro with either WNT3A or small-molecule activators of beta-catenin signaling. Consistent with these results, B16 melanoma cells expressing WNT3A also exhibit decreased tumor size and decreased metastasis when implanted into mice. Genome-wide transcriptional profiling reveals that WNT3A up-regulates genes implicated in melanocyte differentiation, several of which are down-regulated with melanoma progression. These findings suggest that WNT3A can mediate transcriptional changes in melanoma cells in a manner reminiscent of the known role of Wnt/beta-catenin signaling in normal melanocyte development, thereby altering melanoma cell fate to one that may be less proliferative and potentially less aggressive. Our results may explain the observed loss of nuclear beta-catenin with melanoma progression in human tumors, which could reflect a dysregulation of cellular differentiation through a loss of homeostatic Wnt/beta-catenin signaling.