Survival impact of immediate complete lymph node dissection for Chinese acral and cutaneous melanoma with micrometastasis in sentinel nodes: a retrospective study

Sentinel node biopsy (SNB) has become a critical part of standard surgical treatment for melanoma with no clinical metastatic evidence. However, for patients with a positive sentinel node, the MSLT-II and DeCOG-SLT trials have shown that immediate complete lymph node dissection (CLND) does not bring further survival benefits. There is still an argument among the Chinese population dominated by acral subtypes on whether CLND can be omitted. Thus, this study aims to investigate the impact of immediate CLND on relapse-free survival (RFS) in Chinese melanoma patients with a positive sentinel node. Patients with acral or cutaneous melanoma of clinical Stages I-II who received SNB procedure and were detected with nodal micrometastasis were retrospectively collected at Fudan University Cancer Center (FUSCC) from January 2017 to December 2021. The clinicopathologic features and prognostic factors for RFS were analyzed. Out of 381 patients who received SNB in the past 5 years, 130 (34%) cases with SN micrometastasis detected were included in this study. Ninety-nine patients underwent immediate CLND while the other 31 patients received observation alone. Among patients who received CLND, the non-SN(NSN)-positive rate was 22.2%. Most of the clinicopathologic factors were balanced well between the CLND and non-CLND groups. However, more patients in the CLND group were detected with BRAF and NRAS mutation (P = 0.006) and received adjuvant PD-1 monotherapy (P = 0.042) as well. There were slightly fewer N1 patients in the CLND group, although the difference did not reach statistical significance (P = 0.075). The study found no significant difference in RFS between the two groups (P = 0.184). Even for patients with the acral subtype (P = 0.925), primary T4 lesion (P = 0.769), or presence of ulceration (P = 0.249), immediate CLND did not bring more survival benefits. Immediate CLND did not bring further RFS benefit for Chinese melanoma patients with SN micrometastasis in real-world clinical practice, even for patients with acral subtype or more tumor burden such as thick Breslow invasion and ulceration.