Fig. 2

Early detection methylation marker validation using fecal DNA from healthy controls and CRC patients. a Receiver operating characteristic (ROC) curve for marker validation of GDNF, HAND2, SLC35F3, SNAP91 and SORCS1 on fecal DNA to determine optimal sensitivity/specificity. The jagged lines indicate the different ROC curves for each independent marker. The dashed line represents the line of no discrimination between good and bad classification. b Methylation frequency (%) of single markers in fecal DNA of healthy controls (white bar) and CRC patients (black bar). The exact number of methylated samples is indicated in the table below for both groups (methylated samples/total number samples). For the healthy control group, the specificity is given; for carcinomas the sensitivity was determined. Pearson’s chi-square test was used to calculate P values. c ROC curve for the best performing marker panel (GDNF/SNAP91) based on the cutoffs for GDNF and SNAP91. The jagged (green) line indicates the ROC curve for this specific panel. The gray line represents the line of no discrimination between good and bad classification. d Methylation frequency of the GDNF/SNAP91 marker panel in fecal DNA of healthy controls (white bar) and carcinomas (dark gray bar). Fisher’s exact test was used to calculate P values. e ROC curve for the best performing marker panel (SLC35F3/SNAP91) without cutoff. f Methylation frequency of the SLC35F3/SNAP91 marker panel in fecal DNA of healthy controls (white bar) and carcinomas (dark gray bar). Fisher’s exact test was used to calculate P values