TWIST1 and colonic neoplasm: For the basic performance test of the CORD assay to detect hypermethylated cancer-derived DNA against a background of blood-derived DNA, we spiked DNA from colon cancer cell line HCT116 (control DNA for methylation of TWIST1 and SEPT9) at ratios of 100%, 50%, 10%, 5%, 1.1%, 0.11%, and 0% into DNA extracted from leukocyte DNA (control DNA for unmethylation of TWIST1 and SEPT9) and measured the methylation levels of TWIST1 and SEPT9 for each sample.