Highly sensitive diagnostic method for colorectal cancer using the ratio of free DNA fragments in serum

Objectives: The correlations of the ratio of long-/short-chain DNA fragments in blood with the existence of cancer and the clinicopathological features of colorectal cancer (CRC) were examined. The potential use of this ratio for diagnostic screening was evaluated.Methods: DNA concentrations were amplified using Alu247 for long-chain DNA fragments and Alu115 for long- and short-chain DNA fragments. The Alu247/115 ratio was calculated for 60 patients with CRC and 24 healthy volunteers. The correlation of the Alu247/115 ratio with clinicopathological variables and the efficacy of this ratio as a tumor marker were examined. The Alu247/115 ratio cut-off value was set using a receiver operating characteristic (ROC) curve.Results: The Alu247/115 ratio was significantly higher in patients with CRC than in healthy volunteers (P