Importance: Melanoma is among the most common malignant neoplasms in the United States, with 91 270 cases estimated to be diagnosed in 2018. Since 2012, Mohs micrographic surgery (MMS) has gained popularity in the treatment of melanoma in situ. Although current guidelines for invasive melanoma without nodal metastases recommend surgery with wide margin excision (WME), use of MMS for this disease has increased as well, particularly in early stages. How the survival outcomes after each procedure compare with one another for early-stage invasive melanoma is unknown to date.

Objective: To evaluate overall survival of patients with stage I melanoma defined by the American Joint Committee on Cancer Cancer Staging Manual, 8th edition (AJCC-8) after MMS vs traditional WME.

Design, setting, and analysis: This retrospective cohort study includes all patients with AJCC-8 stage I melanoma who underwent MMS or WME in the National Cancer Database with a diagnosis from January 1, 2004, through December 31, 2014. The National Cancer Database includes all reportable cases from Commission on Cancer-accredited facilities and represents approximately 50% of all newly diagnosed melanoma cases in the United States. Data were analyzed from November 13, 2018, through June 9, 2019.

Exposures: MMS vs WME.

Main outcomes and measures: Overall survival evaluated using multivariable Cox proportional hazards regression analysis.

Results: A total of 70 319 eligible patients (52.3% male and 47.7% female; median [SD] age, 57.0 [16.2] years) were identified, including 67 085 treated with WME and 3234 treated with MMS. Multivariable Cox proportional hazards regression survival analysis controlling for clinical and tumor factors revealed that treatment with MMS was associated with a modest improvement in overall survival relative to WME (hazard ratio [HR], 0.86; 95% CI, 0.76-0.97). Propensity score-matched analysis of cohorts of patients treated with MMS vs WME also found modestly improved survival for those treated with MMS (HR, 0.82; 95% CI, 0.68-0.98). Academic facilities were more likely to use MMS than nonacademic facilities (odds ratio, 2.03; 95% CI, 1.88-2.18).

Conclusions and relevance: These findings suggest that Mohs surgery may provide an alternative approach to traditional WME for appropriately selected cases of AJCC-8 stage I melanoma without compromising patient survival.