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. Limitations: Single-institution, retrospective review. 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.