Article Type

Original Study


Objective The aim was to study whether the concentration of circulating cell-free DNA (ccf-DNA) in serum could be used as a diagnostic biomarker for patients with colorectal cancer (CRC). Background Early diagnosis of CRC represents the best chance for cure. The present screening programs have limited sensitivity and specificity. Increased levels of ccf-DNA provide promising biomarker for several diseases including cancer. It has been postulated that tumor necrosis causes release of DNA of varying sizes which is in contrast to apoptosis of normal cells where smaller amount of DNA fragments are released. Patients and methods This study was carried out on 80 participants classified into the following groups: group I included 40 patients with CRC, group II included 20 patients with benign diseases in colon and rectum, and group III included 20 healthy controls. Laboratory investigations including carbohydrate antigen 19-9 serum level by enzyme-linked immunosorbent assay technique and quantitative analysis of ccf-DNA through detection of short (115 bp) DNA fragments in serum by real-time quantitative PCR by amplifying the Associative Location Unit (ALU) repeats (ALU-qPCR) were performed for all participants. Results The median absolute serum ALU115 levels in CRC group was significantly higher than those in intestinal polyp and normal control groups (P = 0.001) Conclusion It was concluded that serum DNA concentrations may be valuable in early diagnosis, monitoring of progression, and prognosis of CRC.