Survival after lymph node dissection, radiotherapy, and combined treatment in sentinel node-positive stage IIIA Merkel cell carcinoma

BACKGROUNDMerkel cell carcinoma (MCC) has a high risk of regional lymphatic metastasis. In cases of lymphatic micrometastasis, an evidence-based clinical approach is missing.

OBJECTIVETo assess survival outcomes following complete lymph node dissection (CLND), radiation (RTX), or CLND plus RTX (CLND + RTX) in patients with stage IIIA MCC.

METHODSA systematic search was conducted in MEDLINE, Embase, and the Cochrane Library. Pooled survival rates were calculated using random-effects models. Comparative effectiveness of interventions was assessed via network meta-analysis.

RESULTSEight studies, including 1825 patients, were analyzed. Pooled 1- and 3-year survival rates (overall survival and MCC-specific survival) following CLND (regardless of RTX) were 93% (95% CI, 89%-96%) and 71% (95% CI, 64%-77%), showing no significant difference compared with patients without CLND. Furthermore, relative risk ratios comparing RTX (regardless of CLND status) with no RTX demonstrated no significant differences for overall survival at either 1 or 3 years. Finally, a network meta-analysis also did not show superiority among CLND only, RTX only, and CLND + RTX in patients with stage IIIA MCC.

LIMITATIONSThe limited number of observational studies, data heterogeneity, missing data regarding immunotherapies, and low evidence levels according to the GRADE restrict definitive conclusions.

CONCLUSIONSFindings underscore the need for large, prospective clinical trials to define optimal treatment strategies for patients with stage IIIA MCC.

PROSPERO NUMBERCRD42025636348.

Abstract from PubMed