Objectives: Thick melanomas, defined as ≥4 mm in thickness, represent ~5% of new melanoma diagnoses and have been associated with poor overall survival (OS). Ultrathick melanomas, those lesions ≥8 mm in thickness, have been associated with worse survival. We sought to compare prognostic factors for thick and ultrathick melanoma.
Methods: Retrospective analysis of a prospective database of all patients receiving an operation for melanoma, June 2005 to December 2016 was performed. Multivariate Cox proportional hazards regression analyses were performed to identify predictors of progression-free survival (PFS) and OS.
Results: Of 95 patients with thick melanoma, 37 (39%) had ultrathick tumors (≥8 mm thick). Thick and ultrathick lesions were not significantly different on the basis of tumor location, ulceration, mitotic rate, lymphovascular invasion, or performance or positivity of sentinel node biopsy or therapeutic lymphadenectomy. Disease recurrence was identified in 38 patients overall (40%), more commonly in ultrathick disease (55% vs. 29%, P=0.008). Serum neutrophil to lymphocyte ratio (NLR) was available for 36 patients, of whom 23 (64%) had high NLR (>3.0). Decreased PFS was independently associated with ultrathick tumors (HR, 2.9; P=0.003), head/neck location (HR, 2.6; P=0.023), and positive lymph nodes (HR, 3.3; P=0.004). Decreased OS was independently associated with high NLR (HR, 5.0; P=0.042).
Conclusions: Disease progression was higher in the ultrathick melanoma group. Thicker tumors, head/neck location, and positive lymph nodes were associated with decreased PFS. High NLR was associated with decreased OS. Ultrathick melanomas represent advanced malignancy; however, patients may derive benefit from surgical treatment to achieve locoregional control.