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A Critical Evaluation of Ultra-Thick Melanoma: Balancing Tumor Biology and Local Control
*Andrew M Blakely1, *Danielle S. Comissiong2, Michael P. Vezeridis1, Thomas J. Miner1
1Rhode Island Hospital/Brown University, Providence, RI;2Brown University, Providence, RI
Objective: Among patients with advanced melanoma, ultra-thick (≥6mm) lesions are particularly high-risk for disease progression and treatment failure. Given such aggressive tumor biology, some surgeons have advocated less aggressive treatment approaches.
Design: Retrospective review of prospectively-maintained database.
Setting: Academic tertiary-care center.
Patients: Adult patients who underwent wide local excision (WLE) with/without sentinel lymph node biopsy (SLNB) for thick (≥4mm) melanoma, June 2005 to June 2015.
Interventions: WLE, SLNB.
Main Outcome Measures: Disease recurrence.
Results: 80 patients were identified with thick melanoma (≥4mm), of whom 44 (55.0%) had ultra-thick lesions (≥6mm). Primary tumor thickness was 4-39mm, with mean 8.2mm. Fifty-one tumors were ulcerated (63.8%); 76 had mitotic rate≥1 (95.0%). There was no significant difference between thick and ultra-thick lesions for tumor location, ulceration, mitotic rate, lymphovascular invasion, or positive SLNB. Ultra-thick patients underwent SLNB less frequently (50.0% versus 77.8%, p=0.011). Disease recurrence was identified in 29 patients (36.3%): 10 local, 10 regional, 9 distant. Although overall survival was not significantly different (ultra-thick: 455 days versus thick: 677 days, p=0.091), disease recurrence was detected more commonly in ultra-thick disease (n=21, 47.7% versus n=8, 22.2%; p=0.018). Median time to recurrence was 300 days (range 34-1176). On multivariate analysis, ultra-thick tumor depth was independently associated with increased risk of both local (p=0.043) and regional (p=0.037) recurrence.
Conclusions: Ultra-thick melanoma often indicates aggressive tumor biology with higher rates of locoregional recurrence than thick lesions, lending itself to under-treatment. However, operative treatment is not futile, as durable locoregional control is still possible for many patients. Identifying those patients prospectively remains challenging. Clinical decision-making that considers patients’ treatment goals while balancing the desire for local control against aggressive tumor biology is paramount.
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