Current guidelines recommend local excision margin (EM) with 1 to 2 cm on primary Merkel cell carcinoma (MCC) sites.We compared survival outcomes of patients with MCC who were treated with different surgical interventions.A retrospective analysis of MCC cases in the Surveillance, Epidemiology, and End Results database was performed using the Kaplan-Meier, competing risk, and Cox proportional hazards regression model analyses. Influence of age, T stage, American Joint Committee on Cancer stage, adjuvant radiotherapy, and other subgroups were also analyzed by pairwise log rank test.Our results indicated a significant association between local destruction method and inferior survival, while an EM2 cm showed significantly higher overall survival. In addition, the competing risk analysis depicted a similar trend as the Kaplan-Meier analysis, and considerably reduced estimated cumulative incidence. Further subgroup pairwise analysis demonstrated that the EM2 cm method had better survival in patients who were60 years of age, having smaller tumor diameters (T1 and T2) or having undergone adjuvant radiotherapy (P .05). In contrast, different EMs did not show any significant association with survival rate in patients ≥75 years of age or stage III tumors.This study was not prospectively randomized without relapse data.It is challenging to make optimal EM recommendations, because surgical options may depend on individual case situations. Further prospective randomized studies are warranted.
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