Importance of sentinel lymph node biopsy in patients with thin melanoma.

HYPOTHESIS: The status of the sentinel node (SN) confers important prognostic information for patients with thin melanoma.

DESIGN, SETTING, AND PATIENTS: We queried our melanoma database to identify patients undergoing sentinel lymph node biopsy for thin (< or =1.00-mm) cutaneous melanoma at a tertiary care cancer institute. Slides of tumor-positive SNs were reviewed by a melanoma pathologist to confirm nodal status and intranodal tumor burden, defined as isolated tumor cells, micrometastasis, or macrometastasis (< or =0.20, 0.21-2.00, or >2.00 mm, respectively). Nodal status was correlated with patient age and primary tumor depth (< or = 0.25, 0.26-0.50, 0.51-0.75, or 0.76-1.00 mm). Survival was determined by log-rank test.

MAIN OUTCOME MEASURES: Disease-free and melanoma-specific survival.

RESULTS: Of 1592 patients who underwent sentinel lymph node biopsy from 1991 to 2004, 631 (40%) had thin melanomas; 31 of the 631 patients (5%) had a tumor-positive SN. At a median follow-up of 57 months for the 631 patients, the mean (SD) 10-year rate of disease-free survival was 96% (1%) vs 54% (10%) for patients with tumor-negative vs tumor-positive SNs, respectively (P < .001); the mean (SD) 10-year rate of melanoma-specific survival was 98% (1%) vs 83% (8%), respectively (P < .001). Tumor-positive SNs were more common in patients aged 50 years and younger (P = .04). The SN status maintained importance on multivariate analysis for both disease-free survival (P < .001) and melanoma-specific survival (P < .001).

CONCLUSIONS: The status of the SN is significantly linked to survival in patients with thin melanoma. Therefore, sentinel lymph node biopsy should be considered to obtain complete prognostic information.