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.