Stratifying SLN incidence in intermediate thickness melanoma patients.

ABSTRACT

BACKGROUND: Guidelines for melanoma recommend sentinel lymph node biopsy (SLNB) in patients with melanomas ≥1 mm thickness. Recent single institution studies have found tumors <1.5 mm a low-risk group for positive SLNB. METHODS: A retrospective review of the Sentinel Lymph Node Working Group multicenter database identified patients with intermediate thickness melanoma (1.01-4.00 mm) who had SLNB, and assessed predictors for positive SLNB. RESULTS: 3460 patients were analyzed, 584 (17%) had a positive SLNB. Univariate factors associated with a positive SLNB included age <60 (p < .001), tumor on the trunk/lower extremity (p < .001), Breslow depth ≥2 mm (p < .001), ulceration (p < .001), mitotic rate ≥1/mm2 (p = .01), and microsatellitosis (p < .001). Multivariate analysis revealed age, location, and Breslow depth as significant predictors. Patients ≥75 with lesions 1.01-1.49 mm on the head/neck/upper extremity and 1.5-1.99 mm without high-risk features had <5% risk of SLN positivity. CONCLUSIONS: Intermediate thickness melanoma has significant heterogeneity of SLNB positivity. Low-risk subgroups can be found among older patients in the absence of high-risk features.