LAUSR

BACKGROUND Sentinel lymph node biopsy (SLNB) is widely used for Merkel cell carcinoma (MCC), however in SLNB positive MCC the role of completion lymph node dissection (CLND) with or without adjuvant radiation therapy is unclear. OBJECTIVE Our goal was to determine the impact of CLND and adjuvant radiation therapy on survival in SLNB positive MCC. MATERIALS AND METHODS We examined 447 patients with MCC with a positive SLNB in the National Cancer Data Base from 2012 to 2015. We compared patients who underwent CLND versus observation with or without adjuvant radiation. RESULTS Compared with CLND and adjuvant radiation (reference) treatment with observation (HR 3.54, CI 1.36-9.18) or CLND alone (HR 2.54, CI 1.03-6.27) were associated with worse overall survival after adjusting for clinicopathologic differences. In contrast treatment with adjuvant radiation alone without CLND was not associated with worse overall survival (HR 1.70, CI 0.74-3.92) compared with CLND and adjuvant radiation (reference). CONCLUSIONS In SLNB positive MCC, CLND alone is associated with worse survival compared with treatment with adjuvant radiation or both CLND and adjuvant radiation.