Sentinel lymph node mapping for thick (≥4-mm) melanoma:: Should we be doing it?

Background: Thick (greater than or equal to4-mm) primary melanomas are believed to be associated with a high incidence of occult distant metastases. The use of sentinel lymph node (SLN) mapping and biopsy in the treatment lesions has been questioned. Methods: A retrospective review of a computerized database identified 114 patients who underwent successful SLN mapping and biopsy from January 1, 1994, to December 31, 1999. Records were reviewed for clinicopathologic features of the patients and their tumors. Survival curves were constructed from Kaplan-Meier estimates and analyzed with log-rank tests and Cox proportional hazards modeling. Results: There were 75 men and 39 women with a mean age of 57 years (range, 24-85 years). The primary tumor sites were head and neck (n = 29; 25.4%), trunk (n = 44; 38.6%), and extremities (n = 41; 36%). Tumor thickness ranged from 4 to 17 mm (median, 5.2 mm; mean, 6.3 mm). Ulceration was present in 40 (35.1%) tumors. Thirty-seven patients (32.5%) had a positive SLN biopsy, and 18 of these patients (48.6%) had a single tumor-positive lymph node after dissection. The mean follow-up was 37.8 months. The overall 3-year survival for SLN-negative patients was 82%, versus 57% for SLN-positive patients (P = .006). Lymph node status and tumor ulceration were independent predictors of overall survival in multivariate Cox regression analysis. Conclusions: The pathologic status of the SLN in patients with thick melanomas is a strong independent prognostic factor for survival, and SLN mapping should be routinely performed.