Value of circulating DNA concentration and integrity as a screening test for detection of cancer in an Egyptian cohort

Background: Cell-free DNA (CFDNA) is extracellular nucleic acids found in cell-free plasma/serum of humans. This study aims to quantitatively measure CFDNA concentration and integrity in patients with malignant and non-malignant diseases and in healthy controls to investigate their value as a screening test for cancer, and then to correlate them with the clinicopathological parameters of cancer patients. Aim: This study included 145 subjects divided into three groups; group I: 83 patients with different types of cancer, group II: 30 patients with benign diseases and group III: 30 normal healthy volunteers as control. One plasma sample was collected from each subject. CFDNA was extracted from plasma and its concentration was measured using Quant-iT™ PicoGreen dsDNA Assay Kit, then CFDNA integrity was detected by conventional PCR for 100, 200, 400 and 800 bp. Results: Results revealed that there was a highly significant difference in the mean level of CFDNA between the cancer group and each of the benign and control groups. AUC of ROC curve for cancer group versus normal and benign groups were 0.968 and 0.928,which indicated the efficiency ofCFDNA as amarker for cancer.As for CFDNAintegrity, normal and benign subjects showed only two bands at 100 and 200 bp, while all cancer patients demonstrated the 100, 200 and 400 bp bands and 78%of cancer patients had the 800 bp whose presence was statistically correlated with vascular invasion. Conclusion: Subjects with CFDNA ≤100 ng/μl would be cancer-free; subjects with CFDNA value ≥600 ng/μl could be diagnosed as cancer patients, while those with CFDNA between 100 and 600 ng/μl will need DNA integrity to identify non-cancer from cancer patients. Thus plasma CFDNA in combination with DNA integrity could be used as a screening test for cancer detection.