Is there a benefit to sentinel lymph node biopsy in patients with T4 melanoma?

BACKGROUND: Controversy exists as to whether patients with thick (Breslow depth >4 mm), clinically lymph node-negative melanoma require sentinel lymph node (SLN) biopsy. The authors examined the impact of SLN biopsy on prognosis and outcome in this patient population. METHODS: A review of the authors' institutional review board-approved melanoma database identified 293 patients with T4 melanoma who underwent surgical excision between 1998 and 2007. Patient demographics, histologic features, and outcome were recorded and analyzed. RESULTS: Of 227 T4 patients who had an SLN biopsy, 107 (47%) were positive. The strongest predictors of a positive SLN included angiolymphatic invasion, satellitosis, or ulceration of the primary tumor. Patients with a T4 melanoma and a negative SLN had a significantly better 5-year distant disease-free survival (DDFS) (85.3% vs 47.8%; P < .0001) and overall survival (OS) (80% vs 47%; P < .0001) compared with those with metastases to the SLN. For SLN-positive patients, only angiolymphatic invasion was a significant predictor of DDFS, with a hazard ratio of 2.29 (P=.007). Ulceration was not significant when examining SLN-positive patients but the most significant factor among SLN-negative patients, with a hazard ratio of 5.78 (P=.02). Increasing Breslow thickness and mitotic rate were also significantly associated with poorer outcome. Patients without ulceration or SLN metastases had an extremely good prognosis, with a 5-year OS >90% and a 5-year DDFS of 95%. CONCLUSIONS: Clinically lymph node-negative T4 melanoma cases should be strongly considered for SLN biopsy, regardless of Breslow depth. SLN lymph node status is the most significant prognostic sign among these patients. T4 patients with a negative SLN have an excellent prognosis in the absence of ulceration and should not be considered candidates for adjuvant high-dose interferon.