Surgical resection margin for T3–T4 primary acral melanoma: a multicenter retrospective cohort study

Although the National Comprehensive Cancer Network (NCCN) guidelines include clear recommendations for the appropriate resection margins in non-acral cutaneous melanoma, the required margin for acral melanoma is controversial. In this retrospective study, we aimed to investigate whether narrow-margin excision is warranted for thick acral melanoma. Records from 277 melanoma patients with stage T3–T4 disease who underwent radical surgery in three centers in China from September 2010 to October 2018 were reviewed. Clinicopathologic data, including age, gender, excision margin (1–2 cm versus ≥ 2 cm), Clark level, Breslow thickness, ulceration, N stage and adjuvant therapy, were included for survival analysis. The patients were followed up until death or March 31, 2021. Log-rank and Cox regression analyses were used to identify prognostic factors for overall survival (OS), disease-free survival (DFS) and local and in-transit recurrence-free survival (LITRFS). Among all enrolled patients, 207 (74.7%) had acral melanoma, and 70 (25.3%) had non-acral cutaneous melanoma. No significant difference in baseline characteristics was identified between non-acral and acral melanoma, except for age (p = 0.004), gender (p = 0.009) and ulceration (p = 0.048). In non-acral melanoma, a resection margin of 1–2 cm was a poor independent prognostic factor for OS [p = 0.015; hazard ratio (HR) (95% CI), 0.26 (0.009–0.77)] and LITRFS [p = 0.013; HR (95% CI), 0.19 (0.05–0.71)] but not for DFS [p = 0.143; HR (95% CI), 0.51 (0.21–1.25)]. Forty-three (20.8%) patients in the acral melanoma group had a 1–2-cm resection margin. The resection margin was not correlated with patients’ OS (p = 0.196 by log-rank analysis, p = 0.865 by multivariate survival analysis), DFS (p = 0.080 by log-rank analysis, p = 0.758 by multivariate survival analysis) or LITRFS (p = 0.354 by log-rank analysis) in acral melanoma. As recommended in the NCCN guidelines, a resection margin ≥ 2 cm is required for non-acral cutaneous melanoma. Meanwhile, a narrow resection margin (1–2 cm) may be safe for patients with acral melanoma.