Clinical Utility of Circulating Tumour DNA (ctDNA) Analysis for Assessing Completeness of Primary Lesion Resection and Disease Stage in Patients with Melanoma: A Systematic Review.

Melanoma is an aggressive cutaneous malignancy with a high recurrence rate even after complete resection. Circulating tumour DNA (ctDNA) has emerged as a promising biomarker for detecting minimal residual disease (MRD), assessing tumour burden, and predicting recurrence. This study aims to evaluate the clinical utility of ctDNA analysis in determining completeness of melanoma resection and disease staging. A systematic review was conducted in accordance with PRISMA guidelines, searching PubMed and Web of Science for studies published between January 2017 and February 2025. Eligible studies assessed ctDNA before, during, or after melanoma resection to evaluate surgical completeness and staging. Studies without perioperative ctDNA assessment or which focused solely on immunotherapy efficacy were excluded. Fourteen studies with 1077 patients met the inclusion criteria. Preoperative ctDNA detection correlated with advanced stage, greater tumour burden, and poorer survival. Postoperative ctDNA persistence was strongly associated with recurrence, often detectable months before clinical relapse. In most patients remaining disease-free, ctDNA cleared within weeks after surgery. ctDNA levels reflected metastatic spread, though sensitivity was lower for brain lesions. Across studies, undetectable postoperative ctDNA was consistently linked to longer recurrence-free survival. Perioperative ctDNA analysis shows promise as a prognostic biomarker for detecting residual disease and anticipating relapse in melanoma. However, heterogeneity in patient cohorts, study design, and ctDNA detection methods limits immediate clinical application. Large, standardized prospective trials are needed to validate ctDNA for perioperative management.