Is head and neck melanoma different from trunk and extremity melanomas with respect to sentinel lymph node status and clinical outcome?

Background: Previous studies showed conflicting and inconsistent results regarding the effect of anatomic location of the melanoma on sentinel lymph node (SLN) positivity and/or survival. This study was conducted to evaluate and compare the effect of the anatomic locations of primary melanoma on long-term clinical outcomes.
Methods: All consecutive cutaneous melanoma patients (n=2,079) who underwent selective SLN dissection (SLND) from 1993 to 2009 in a single academic tertiary-care medical center were included. SLN positive rate, disease-free survival (DFS), and overall survival (OS) were determined. Kaplan-Meier survival, univariate, and multivariate analyses were performed to determine predictive factors for SLN status, DFS, and OS.
Results: Head and neck melanoma (HNM) had the lowest SLN-positive rate at 10.8% (16.8% for extremity and 19.3% for trunk; P=0.002) but had the worst 5-year DFS (P<0.0001) and 5-year OS (P<0.0001) compared with other sites. Tumor thickness (P<0.001), ulceration (P<0.001), HNM location (P=0.001), mitotic rate (P<0.001), and decreasing age (P<0.001) were independent predictive factors for SLN-positivity. HNM with T3 or T4 thickness had significantly lower SLN positive rate compared with other locations (P≤0.05). Also, on multivariate analysis, HNM location versus other anatomic sites was independently predictive of decreased DFS and OS (P<0.001). By Kaplan-Meier analysis, HNM was associated significantly with the worst DFS and OS.
Conclusions: Primary melanoma anatomic location is an independent predictor of SLN status and survival. Although HNM has a decreased SLN-positivity rate, it shows a significantly increased risk of recurrence and death as compared with other sites.