Circulating cell-free DNA: A potential biomarker to differentiate inflammation and infection during radiochemotherapy

• Published in: Radiotherapy and oncology 2018-12, Vol.129 (3), p.575-581
• Main Authors: Zwirner, Kerstin, Hilke, Franz J., Demidov, German, Ossowski, Stephan, Gani, Cihan, Rieß, Olaf, Zips, Daniel, Welz, Stefan, Schroeder, Christopher
• Format: Article
• Language: English
• Subjects: Cell-free nucleic acids; Granulocyte colony-stimulating factor; Infection; Liquid biopsy; Radiotherapy; Toxicity
• ISSN: 0167-8140; 1879-0887
• DOI: 10.1016/j.radonc.2018.07.016

•Elevated cfDNA levels were associated with PEG placement and antibiotic treatment.•CfDNA might differentiate radiation-induced toxicity and severe infections.•Ascending cfDNA levels seem to be related to G-CSF treatment.•Confounders should be considered when interpreting cfDNA levels. Radiochemotherapy is a standard treatment option for patients with head and neck cancer (HNSCC). During radiation, local toxicities are common and need to be differentiated from infections. As levels of circulating cell-free DNA (cfDNA) are known to be elevated during infections, cfDNA might complement clinical parameters. The aim of the study was to investigate the dynamics of cfDNA during radiochemotherapy. In total, 78 blood samples of 20 patients with HNSCC were analysed in this prospective biomarker study. Blood samples were taken before and during treatment. CfDNA levels were quantified fluorometrically and results were compared to laboratory and clinical parameters. Elevated cfDNA levels were associated with the pre-treatment volumes of lymph node metastases (p = 0.0002), gastrostomy tube placement (20.23 ng/ml vs. 9.04 ng/ml (median), p = 0.025), the application of antibiotics (16.47 ng/ml vs. 9.04 ng/ml, p = 0.006) and manifest infections (16.81 ng/ml vs. 9.04 ng/ml, p = 0.010). Furthermore, a significant difference between moderate inflammation (radiation-induced toxicity RTOG grade 2–3) and manifest infections could be observed (8.97 ng/ml vs. 16.81 ng/ml, p = 0.014), allowing for a more pronounced differentiation than by CRP levels (p = 0.119). There might be an association between the application of G-CSF and elevated cfDNA levels. CfDNA levels are correlated with infections during radiochemotherapy and could represent an informative complemental biomarker to drive therapeutic decision-making. Estimated levels of circulating cell-free tumour DNA (ctDNA) in plasma should be interpreted cautiously when monitoring tumour outcome by next-generation-sequencing, as confounders like infections or drug application might influence the fraction of ctDNA in total cfDNA.