Plasma cfDNA for the Diagnosis and Prognosis of Colorectal Cancer

Abstract

Objective. To evaluate the value of cell-free DNA (cfDNA) for the diagnosis and prognosis of colorectal cancer (CRC). Methods. Peripheral blood specimens of 120 CRC patients and 90 healthy volunteers (as a control cohort) were extracted. A quantitative real-time polymerase chain reaction (qRT-PCR) was performed to determine the cfDNA expression. Following correlation analyses for cfDNA and clinical endpoints, a receiver operator characteristic (ROC) curve was established to assess the sensitivity and specificity of cfDNA, CEA, VEGF, and CA125 and for evaluating the disease-free survival (DFS) of patients. Results. The plasma cfDNA level of colorectal cancer patients was significantly higher than that of healthy subjects ( $P<0.05$ ), and after chemotherapy, cfDNA level was significantly lower than that before chemotherapy ( $P<0.05$ ). CA125/CEA/VEGF expression significantly correlated with cfDNA level, but not with cfDNA integrity. There was also a significant correlation between tumor differentiation and the cfDNA level. cfDNA has a higher ROC value than the current tumor biomarkers. Survival analysis showed that the DFS of the low cfDNA expression group was longer (29.99 ± 0.78 months) than that of the high cfDNA expression group (27.66 ± 1.05 months, $P=0.031$ ). Conclusion. The blood cfDNA is associated with the pathological features of CRC clinical cases and represents a possible indicator for CRC diagnosis and prognosis.