Management of acral melanoma with lymph node macrometastasis in the post-MSLT-II era: Focus on the effect and timing of lymph node dissection

Background Limited studies have exclusively investigated the role of completion lymph node dissection (CLND) in acral melanoma (AM) with lymph node macrometastasis (macroLNM). This multicenter study aimed to evaluate the impact of CLND and its performance timing on AM patients with macroLNM. Patients and Methods The study enrolled 384 non-metastatic AM patients with initial or recurrent macroLNM from four tertiary hospitals. These patients were categorized into three groups based on the type of CLND: No CLND, CLND, or therapeutic lymph node dissection (TLND). The CLND group was further divided into early and late groups according to the timing of CLND. Kaplan-Meier and Cox multivariable analyses were performed to assess survival differences. Results Of the total cohort, both the 5-year overall survival (OS) and recurrence-free survival (RFS) in No CLND group were significantly worse than those in CLND and TLND groups (p = 0.009 and p = 0.021, respectively). Multivariate analysis demonstrated that CLND performance remained to be significantly associated with both OS and RFS (all p < 0.05). Among CLND group, CLND timing independently predicted worse RFS (p = 0.049) but not OS at multivariate analysis. Notably, late CLND group tended to significantly have more large-size metastatic nodes. Pearson correlation analysis revealed significant correlation between preoperative time interval and the enlargement in size of lymph node metastasis (r = 0.356, p = 0.002). Conclusion CLND remains crucial for improving prognosis for AM with macroLNM. Furthermore, delayed CLND might lead to larger metastatic lymph nodes and decreased RFS. Thus, performing CLND earlier may be beneficial for this patient population.