Scatterplot representation of marker discovery process and ROC curves.

<p>A (top figure: HM27, bottom figure: HM450), scatterplots of the highest PBL β-value (β-PBL_H) of 10 (HM27) and 2 (HM450) healthy control samples (X-axis) against the associated 10th percentile of CRC tumor β-values (β-CRC₁₀) on the Y-axis. The blue dots represent the eliminated probes (HM27: n = 23,049; HM450: n = 367,833) and the red dots (HM27: n = 695; HM450: n = 30,207) represent the retained probes with a β-CRC₁₀>β-PBL_H or a β-PBL_H<0.2. B, scatterplots of the mean normal colon tissue β-value (β-NC_M) for the retained probes from Panel A (X-axis) against the associated β-CRC₁₀ (Y-axis). The red dots (HM27: n = 512; HM450: n = 28,428) represent the eliminated probes, the green dots represent the retained probes (HM27: n = 183; HM450: n = 1779) with a β-CRC₁₀>β-NC_M or a β-NC_M<0.2. C, scatterplots of the retained probes from Panel B (green) displayed by the difference between β-CRC₁₀ and β-PBL_H (X-axis) against the associated β-CRC₁₀ (Y-axis). The dots within the yellow square are the probes selected for additional filtering against other types of cancer. The white arrows point out the probes of the two candidate markers. D, ROC curves for the probes used in the multiplex reaction based on methylation β-values of 335 independent colorectal cancer samples and 23 independent matched normal colorectal tissue samples (the DNA methylation data of these samples were not used in the marker discovery pipeline). The dark grey color is the area under the curve.