No difference in survival for primary cutaneous Merkel cell carcinoma after Mohs micrographic surgery and wide local excision

Abstract

The preferred treatment for clinically node-negative Merkel cell carcinoma (MCC) is surgical excision in conjunction with sentinel lymph node biopsy. There is limited large-scale research on survival outcomes by surgical approach for management of the primary tumor. To compare overall and MCC-specific survival outcomes in clinically and pathologically node-negative MCC patients treated with wide-local excision (WLE) and Mohs micrographic surgery (MMS) in a nationally representative sample. Overall and MCC-specific survival outcomes for primary MCC tumors contained in the SEER-18 database from 1989 to 2015 were stratified by surgical modality and analyzed via competing risk analysis. A total of 2,359 US adults with MCC were included in the analysis. For overall and MCC-specific survival, there was no significant difference in survival outcomes between WLE and MMS on multivariable analysis ((HR 1.04 [95% CI 0.88 - 1.22]; SHR 0.76 [95% CI 0.53 - 1.09]). Sentinel lymph node biopsy (SLNB) was associated with improved overall survival and MCC-specific survival. Retrospective design of SEER and the lack of covariates such as comorbidities and immunostaining. There is no survival disadvantage for MMS compared to WLE as the surgical modality for primary cutaneous MCC. SLNB should be coordinated prior to MMS.