Factors Influencing Margin Clearance and the Number of Stages of Mohs Micrographic Surgery in Basal Cell Carcinoma: A Retrospective Chart Review

How patient and tumor factors influence clearance margins and the number of Mohs Micrographic Surgery (MMS) stages when treating basal cell carcinoma (BCC) remains widely uncharacterized. It is important to elucidate these relationships, as surgical outcomes may be compared nationally between colleagues. Our objective is to evaluate the relationships between defect size and patient demographics, as well as between BCC subtypes and the number of MMS stages. Our second objective is to compare practice patterns and characteristics of patients requiring MMS at academic centers and private practices. A retrospective chart review was performed using data collected at academic centers (2015-2018) and private practices (2011-2018) of BCC patients older than 18 years old who underwent MMS. In total, 7651 patients with BCC requiring MMS were identified. Academic center adjusted analyses demonstrated clearance margins 0.1 mm higher for every year's increase in age ( < 0.0001) and 0.25 increase in MMS stages for high-risk BCC ( < 0.0001). Private practice adjusted analyses demonstrated clearance margins 0.04 mm higher for every year's increase in age ( < 0.0001). Clearance margins correlate with older age, and additional MMS stages correlate with high-risk BCC, suggesting the role patient and tumor factors may play in predicting tumor clearance and MMS stages.