Role of sentinel lymph node biopsy in patients with thick (>4 mm) primary melanoma

Lymphatic mapping and sentinel lymphadenectomy have become a routine part of the treatment algorithm for primary melanoma. Their role in the management of thick (>4 mm) lesions is evolving. Our purpose was to evaluate the influence of single lymph node (SLN) histology on survival of patients with thick melanomas. A computerized patient database was accessed to obtain records on patients with thick melanomas. Survival curves were constructed with the Kaplan-Meier method, and a Cox regression analysis was used to establish statistical significance. Between 1997 and 2002, 266 SLN biopsy procedures were performed, using both radioisotope and blue dye, in 259 patients with malignant melanoma. Forty-five patients (17%) had thick melanomas. Twenty patients (44%) had at least one positive sentinel lymph node. The mean disease-free survival (DFS) of SLN-positive patients was 44 months compared with 53 months in SLN-negative patients (P = 0.0221). Increasing Breslow thickness was associated with a decrease in DFS, whereas no other histologic parameters such as Clark level, mitotic rate, or ulceration had an influence on DFS. Our data indicate that the status of the SLN node is predictive of disease-free survival in patients with thick melanomas. SLN biopsy is thus justified in patients with thick melanoma.