Fig. 5

Detection of stage IV CRC in liquid biopsy. A pilot study was performed on plasma (300 μl) from 20 colorectal carcinomas (CRC stage IV) and 20 normal individuals. Using cMethDNA, a subset of nine markers found hypermethylated in colon carcinoma tissue (Fig. 1, Table 2) was assayed for circulating cell-free DNA methylation. The TWIST1 marker failed due to technical reasons so it was excluded; the results from the 8-gene panel are shown. A Histogram plot. For each sample (X-axis), the height of the histogram bar indicates the level of cumulative methylation (Y-axis), each colored segment represents an individual gene, and the size of the segment is proportional to the %M of that gene. B Box–whiskers plot. Comparing CRC versus normal control plasma, significantly higher cumulative methylation of the 8-gene panel was observed in stage IV CRC (X-axis; Mann–Whitney, P < 0.0001). C Receiver operating characteristic (ROC). The 8-gene panel detected stage IV CRC versus normal controls with a sensitivity of 95% and specificity of 100% (AUC 0.996, P < 0.0001) at a threshold of 8.5 CMI. Additional file 1: Figs. S2, S3 show performance of the individual 8 markers in plasma using box–whiskers plots, Mann–Whitney and ROC analyses. Additional file 1: Fig. S4 shows the performance of the same panel in tissue using QM-MSP