Factors predicting outcomes of patients with high-risk squamous cell carcinoma treated with Mohs micrographic surgery

Background: There is limited literature on the long-term outcomes and prognostic factors of high-risk cutaneous squamous cell carcinomas (hrSCC) treated with Mohs micrographic surgery (MMS).Objective: To determine the rates of local recurrence, metastatic disease, and disease-specific death in hrSCCs treated with MMS and patient or tumor factors associated with poor outcomes.Methods: Single-institution, retrospective cohort analysis of hrSCC treated with MMS alone and MMS with adjuvant therapy.Results: A total of 882 cases of hrSCC treated with MMS were identified, of which 842 were treated with MMS alone, with a median follow-up time of 2.4 years. The rate of local recurrence was 2.5%, of metastatic disease was 1.9%, and of disease-specific death was 0.57%. Perineural invasion, poor differentiation, and immunosuppression were significantly associated with poor outcomes. In propensity score-matched case patients treated with adjuvant therapy and control patients treated with Mohs alone, there was no significant difference in progression-free survival, but matching was imperfect.Conclusions: MMS remains an effective treatment for hrSCC. Current SCC staging systems may be limited by inconsistent inclusion of poor differentiation. Immunosuppression, especially transplant, should be considered a high-risk clinical feature. Further study is needed on the effect of adjuvant treatment.