Stratifying SLN incidence in intermediate thickness melanoma patients

Abstract

BackgroundGuidelines 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. MethodsA 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. Results3460 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. ConclusionsIntermediate thickness melanoma has significant heterogeneity of SLNB positivity. Low-risk subgroups can be found among older patients in the absence of high-risk features.