Meta-analysis of Sentinel Lymph Node Positivity in Thin Melanoma (≤1 mm)

BACKGROUND: Despite the lack of an established survival benefit of sentinel lymph node (SLN) biopsy, this technique has been increasingly applied in the staging of thin (<= 1 mm) melanoma patients, without clear evidence to support this recommendation. The authors performed a meta-analysis to estimate the risk, potential predictors, and outcome of SLN positivity in this group of patients. METHODS: MEDLINE, EMBASE, and Cochrane databases were searched for rates of SLN positivity in patients with thin melanoma. The methodologic quality of included studies was assessed using the Methodological Index for Non-Randomized Studies criteria. Heterogeneity was assessed using the Cochran Q statistic, and publication bias was examined through funnel plot and the Begg and Mazumdar method. Overall SLN positivity in thin melanoma patients was estimated using the DerSimonial-Laird random effect method. RESULTS: Thirty-four studies comprising 3651 patients met inclusion criteria. The pooled SLN positivity rate was 5.6%. Significant heterogeneity among studies was detected (P = .005). There was no statistical evidence of publication bias (P = .21). Eighteen studies reported select clinical and histopathologic data limited to SLN-positive patients (n = 113). Among the tumors from these patients, 6.1% were ulcerated, 31.5% demonstrated regression, and 47.5% were Clark level IV/V Only 4 melanoma-related deaths were reported. CONCLUSIONS: Relatively few patients with thin melanoma have a positive SLN. To the authors' knowledge, there are no clinical or histopathologic criteria that can reliably identify thin melanoma patients who might benefit from this intervention. Given the increasing diagnosis of thin melanoma, in addition to the cost and potential morbidity of this procedure, alternative strategies to identify patients at risk for lymph node disease are needed. Cancer 2009;115:869-79. (C) 2008 American Cancer Society.