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Updated: Dec 17, 2025
Detection of Cell-Free DNA in Blood Plasma Samples of Cancer Patients
Published on: September 9, 2020
The predictive and prognostic significance of cell-free DNA concentration in melanoma
R Váraljai1, S Elouali1, S S Lueong2,3
1Department of Dermatology, University Hospital of Essen, University Duisburg-Essen and German Cancer Consortium (DKTK) partner site Essen/Düsseldorf, Essen, Germany.
Background:
Melanoma is the leading cause of skin cancer-related deaths worldwide. While there have been significant improvements in the treatment of advanced melanoma in the past decade, biomarker development lagged behind.
Objectives:
The majority of liquid biopsy biomarkers rely on the analyses of oncogenic mutations; however, about 20% of melanoma patients are wild type. Therefore, validation of universal predictive and prognostic biomarkers is urgently needed.
Methods:
We analysed plasma samples in a discovery cohort (n = 20) and expansion cohort (n = 166) of metastatic melanoma patients and healthy donors (n = 116). Total plasma circulating cell-free DNA (cfDNA) concentrations were measured on the Qubit® platform using assays for single-(ss) and double (ds)-stranded DNA, DNA spectrophotometry and RNase P qPCR. We explored the diagnostic, predictive and prognostic potential of cfDNA concentration by bio-statistical methods and established a cfDNA threshold for risk stratification.
Results:
Our selected best method was Qubit® dsDNA assay which quantified higher plasma cfDNA concentrations in melanoma patients than in healthy controls (AUC 72%). Measurement of baseline cfDNA concentration revealed that high cfDNA was associated with presence of metastases and higher AJCC stage (P < 0.05). Furthermore, high baseline cfDNA was an indicator of shorter overall survival in patients with oncogenic mutations (HR 2.12, P = 0.0008), and in wild-type patients (HR 5.55, P < 0.0001).
Conclusions:
We provide evidence that total cfDNA can be used as a biomarker for melanoma irrespective of the tumour genotype and can provide information on tumour load, risk of progression and risk of death.
