Circulating cell-free DNA in melanoma patients

Plasma DNA concentration has been identified as a non-specific biomarker of tumor presence. Hypothesis on the cell-free DNA (cfDNA) origin are still controversial and details on the mechanism of release are not completely disclosed. Never the less several groups could demonstrate an increase of cfDNA in different types of cancer and, with the aim to identify DNA of certain tumor origin, DNA variants frequently associated to each cancer type had been detected and quantified in plasma of subjects affected by neoplastic disease. Analogously epigenetic changes frequently detected in tumours have represented the target of measurements aimed at the identification of tumour specific biomarkers. The aim of the present study was to identify a sequential multi-marker panel in cfDNA able to increase the predictive capability in the diagnosis of cutaneous melanoma in comparison with each single marker alone. We adopted a real time PCR (qPCR) approach based on the quantification of amplicons by means of hydrolysis probes to test each plasma sample for total cfDNA concentration, cfDNA integrity, BRAFV600E mutation and RASSF1A promoter methylation. These measurements were performed in a case study composed of 76 melanoma patients and 63 healthy controls. These markers have been used in a panel in all patients in a fixed manner, thus representing a simple model that might be adopted by any laboratory and easily interpreted by clinicians. The serial assessment of the four parameters allows the identification of melanoma patients with 100% sensitivity and 96.8% specificity. We can hypothesize to test the diagnostic as well as prognostic ability of this multimarker panel to investigate also other cancer types.