Total serum DNA and DNA integrity: diagnostic value in patients with hepatitis B virus-related hepatocellular carcinoma

Aims: This study aimed to test the diagnostic utility of the total serum cell-free DNA (cfDNA) and DNA integrity index for detection of hepatitis B virus (HBV)-related hepatocellular carcinoma (HOC). Methods: We initially evaluated the sodium iodide (Nal) method, Triton/Heat/Phenol (THP) protocol and QIAamp Kit for cfDNA extraction. Then cfDNA was isolated from the sera of 80 patients with HBV-related HOC, 80 patients with chronic HBV infection and 50 healthy subjects, and quantified by real-time quantitative polymerase chain reaction (qPCR) amplification of beta-actin genomic DNA fragments using two sets of primers of 100 and 400 bp. DNA integrity was calculated as the ratio of 400 bp to 100 bp beta-actin fragments. Results: The THP approach was not only superior to the other two methods in terms of DNA quantity, but also was simpler, more rapid, and less costly. Serum DNA integrity in HOC patients was significantly higher than that in HBV patients or healthy controls. As for total cfDNA levels, although a significant difference was found between HOC patients and healthy individuals, no significant difference was found between HBV patients with and without HOC. DNA integrity was associated with tumour size, TNM stage, lymph node and distant metastasis. DNA integrity had a higher sensitivity and specificity in discriminating HOC from HBV patients than total DNA. Conclusions: The THP method is preferred for extraction of cfDNA. DNA integrity is a promising molecular biomarker for detecting HOC in patients with chronic HBV infection; it reflects the progression and metastatic potential of the tumour.