No Disease-Specific Survival Benefit With Wide Margin Mohs Surgery for Lentigo Maligna Melanoma

Abstract

L entigo maligna melanoma (LMM) represents approximately 4% to 15% of invasive melanoma subtypes and commonly occurs on the head and neck in chronically sun-damaged skin. 1 Surgical removal is considered the gold-standard treatment, and previous studies have reported reduced recurrence rates in LMM when treated with Mohs micrographic surgery (MMS) compared with standard wide local excision. 2 Currently, surgical margins for LMM are based on tumor thickness and can range anywhere from 1 to 3 cm; however, optimal margins in the context of MMS are still a point of debate. 3 Herein, this study aims to evaluate disease-specific survival (DSS) of patients with LMM treated with narrow and wide surgical margin-MMS.The 2000 to 2020 Surveillance, Epidemiology, and End Results (SEER) database was used to identify biopsyconfirmed cases of LMM patients (ICD-O-3 histology code 8,742/3; primary site code C44.0-44.9) treated with MMS. Patients with lentigo maligna (in situ) and distant-stage disease were excluded from this study. Surgical margins for MMS were defined by the SEER database as narrow (#1 cm) or wide (.1 cm). Statistical analysis was completed using SPSS version 29.0 and included Chi-squared, Mann-Whitney U, Kaplan-Meier and log-rank, and multivariate Cox proportional hazards (significance p , .05).A total of 514 patients were identified, of which 84.4% were treated with narrow-margin MMS and 15.6% with wide-margin MMS (Table 1). Majority identified as male (66.5%), ages 70 to 79 (31.1%), with localized disease (98.4%), and having tumors located on the head and neck (72.9%). There was a significant association between margin size and rural/urban living (p 5 .024), where higher rates of urban patients received treatment with wide-margin MMS (17.0% vs 6.8%), whereas rural patients more frequently underwent narrow-margin MMS (93.2% vs 83.0%). On univariate Kaplan-Meier analysis, there was no significant difference in 5-and 10-year DSS rates between patients treated with narrow (96.0% and 95.0%) and wide margins (97.0% and 91.0%) (p 5 .70; See Supplemental Digital Content 1, Figure 1, http://links.lww. com/DSS/B487). A multivariate Cox regression adjusting for age, sex, rural-urban living, annual income, localized/ regional disease stage, and Breslow thickness revealed no significant difference in disease-specific mortality risk between wide and narrow-margin MMS (reference: narrow margins; aHR 3.37; 95% CI 0.25-45.96; p 5 .36).To our knowledge, this study is the first to compare DSS outcomes between narrow and wide-margin MMS for invasive LMM patients. A previous study by Zitelli and colleagues 4 found that surgical margins of 1.5 cm were required to excise 97% of LMs and LMMs of the head and neck. By contrast, a retrospective cohort analysis by O'Hern