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Updated: May 30, 2026
Detection of Cell-Free DNA in Blood Plasma Samples of Cancer Patients
Published on: September 9, 2020
Circulating cell-free DNA in plasma of melanoma patients: qualitative and quantitative considerations
Pamela Pinzani1, Francesca Salvianti, Sara Zaccara
1Department of Clinical Physiopathology, University of Florence, Viale Pieraccini 6, 50139 Florence, Italy. p.pinzani@dfc.unifi.it
Abstract:
DNA integrity in blood is an emerging biomarker in cancer. Here we report a real time PCR approach for the absolute quantification of four amplicons of 67, 180, 306 and 476 bp in cutaneous melanoma. Three different integrity indexes (180/67, 306/67 and 476/67 ratios) were tested for their ability to reflect differences in plasma cell-free DNA (cfDNA) fragmentation in 79 patients affected by cutaneous melanoma and 34 healthy subjects. All the three integrity indexes showed higher values in melanoma patients in comparison with healthy subjects. According to ROC curve analysis, the ratio 180/67 is the most suitable index to be used in cancer patient selection, even if the combination of the 3 indexes gives the best performance in terms of clinical sensitivity. The most represented fragments in plasma of melanoma patients are those comprised between 181 and 307 bp, while in healthy subjects there is a prevalence of shorter fragments (67-180 bp). In conclusion, DNA integrity indexes can be considered suitable parameters for monitoring cfDNA fragmentation in melanoma patients.
Insights
DNA integrity in blood, a novel cancer biomarker, shows distinct fragmentation patterns in melanoma patients. Specific DNA integrity indexes can effectively differentiate melanoma patients from healthy individuals, aiding in cancer detection.
Area of Science:
- Oncology
- Molecular Biology
- Biochemistry
Background:
- Cell-free DNA (cfDNA) integrity in blood is an emerging biomarker for cancer detection.
- Altered cfDNA fragmentation patterns are observed in various cancers, including melanoma.
Purpose of the Study:
- To investigate the utility of DNA integrity indexes as biomarkers for cutaneous melanoma.
- To quantify cfDNA fragmentation using real-time PCR and assess its diagnostic potential.
Main Methods:
- Absolute quantification of four different amplicon lengths (67, 180, 306, 476 bp) using real-time PCR.
- Calculation and comparison of three DNA integrity indexes (180/67, 306/67, 476/67 ratios) in 79 melanoma patients and 34 healthy subjects.
- Receiver Operating Characteristic (ROC) curve analysis to determine the most suitable index for patient selection.
Main Results:
- All three integrity indexes were significantly higher in melanoma patients compared to healthy subjects.
- The 180/67 ratio demonstrated the highest suitability for melanoma patient selection via ROC analysis.
- Melanoma patients showed a prevalence of longer cfDNA fragments (181-307 bp), while healthy subjects had shorter fragments (67-180 bp).
Conclusions:
- DNA integrity indexes are valuable parameters for monitoring cfDNA fragmentation in cutaneous melanoma.
- The 180/67 ratio and combined indexes show promise for clinical application in melanoma diagnosis and monitoring.
- cfDNA integrity analysis offers a non-invasive approach to assess melanoma status.
