Background: The clinical significance of isolated tumor cells (ITCs) in the melanoma-draining sentinel nodes (SNs) is unclear.
Methods: Records of patients who underwent SN biopsy (SNB) for stage I/II melanoma at our institute between 1991 and 2003 were reviewed to identify patients whose SNs were tumor-free or contained only ITC (<or=0.2 mm). Tumor-positive SNs were reevaluated by the study pathologist to confirm the diagnosis and microstage the SN. Characteristics of the primary melanoma, tumor status of regional lymph nodes, and other prognostic variables were recorded. Melanoma-specific survival (MSS) rates were compared by the log-rank test.
Results: Of 1,382 patients who underwent SNB, 1,168 (85%) had tumor-free SNs; among the 214 remaining patients with tumor-positive SNs, 57 had metastases limited to ITC. Completion lymphadenectomy (CLND) was performed in 52 of 57 patients: six (12%) had metastases in nonsentinel nodes (NSNs). At a median follow-up of 57 months, 5-year and 10-year MSS was significantly higher (P = .02) for the 1168 patients with tumor-negative SNs (94 +/- 1% and 87 +/- 2%, respectively) than the 57 patients with ITC-positive SNs (89 +/- 4% and 80 +/- 7%, respectively). Multivariate analysis identified ITC (P = .002), Breslow's thickness (P < .0001), ulceration (P < .0001), and primary site (P = .04) as significant for MSS.
Conclusion: Patients with ITC in SNs have a significantly higher risk of melanoma-specific death than those with tumor-negative SNs. The 12% incidence of nonsentinel node metastasis is similar to rates reported for patients with more extensive SN involvement. Patients with ITC should be considered for CLND.