A Meta-analysis of the Prognostic Significance of Sentinel Lymph Node Status in Merkel Cell Carcinoma

BACKGROUND: Merkel cell carcinoma is an aggressive cutaneous neoplasm with a high propensity to metastasize to lymph nodes. OBJECTIVE: The objective of this study was to determine the prognostic significance of sentinel lymph node status in patients with Merkel cell carcinoma. METHODS: A meta-analysis of case series of patients with Merkel cell carcinoma managed with sentinel lymph node biopsy was performed. RESULTS: Forty of 60 patients (67%) had a biopsy-negative sentinel lymph node; 97% of this group had no recurrence at 7.3 months median follow-up. Twenty patients (33%) had a biopsy-positive sentinel lymph node; 33% of this group experienced local, regional, or systemic recurrence at 12 months median follow-up. Risk of recurrence or metastasis was 19-fold greater in biopsy-positive patients (odds ratio, 18.9; p = 0.005). None of 15 biopsy-positive patients who underwent therapeutic lymph node dissection experienced a regional recurrence; 3 of 4 who did not receive therapeutic lymphadenectomy experienced regional recurrence. CONCLUSION: Sentinel lymph node positivity is strongly predictive of a high short-term risk of recurrence or metastasis in patients with Merkel cell carcinoma. Therapeutic lymph node dissection appears effective in preventing short-term regional nodal recurrence. Aggressive adjuvant treatment should be considered for patients with positive sentinel lymph nodes.