Background: Analysis of circulating cell-free DNA in blood is considered as a liquid biopsy, which enables non-invasive and repetitive investigation of the tumor DNA. The potential clinical usefulness of circulating DNA is frequently examined in lung cancer. Thus, our aim was assessment if chemotherapy influences the circulating DNA concentration.
Patients and methods: Fifty-seven lung cancer patients in advanced stages of the disease were examined. Quantification of circulating DNA was determined by TERT amplification.
Results: Distant metastases and chemotherapy were significantly connected with circulating DNA level. Patients treated with conventional chemotherapy had statistically lower circulating DNA levels when compared to patients not treated with chemotherapy. Histological types of tumor and smoking status were not associated with circulating DNA concentration. In this study, we have also genotyped the EGFR mutations in exon 19 of circulating DNA using the TaqMan PCR assays. One patient carried a deletion (2235-49del in EGFR), which has been confirmed by sequencing.
Conclusions: Circulating DNA is easy to obtain, convenient biological material, although quantitative analysis cannot be used as diagnostic tool, but it can be applied to determination of EGFR mutations, basis of the tyrosine kinase inhibitors application.
Keywords: Circulating DNA; cell-free DNA; chemotherapy; liquid biopsy; lung cancer.