Fig. 2

Discovery of DNA methylation markers to detect LNM in EGC tissue. a Unsupervised hierarchical clustering of 60 methylation markers differentially methylated between positive lymph node metastatic samples (LNM+, n = 23) and negative lymph node metastatic samples (LNM−, n = 24) in the discovery cohort. The β-value represented the methylation level of markers. A β-value of zero represents no methylation, whereas 1 represents full methylation. b Methylation level distributions of CCDC166 between positive lymph node metastatic samples (LNM+, n = 23) and negative lymph node metastatic samples (LNM−, n = 24) as represented by β-value from genome-wide methylation sequencing in the discovery cohort. c Methylation level distributions of CCDC166 between positive lymph node metastatic samples (LNM+, n = 23) and negative lymph node metastatic samples (LNM−, n = 24) as represented by Δ Ct values from qPCR-based methylation analysis in the discovery cohort. The data are shown as median with 95% confident intervals. Statistical significance was assessed using a non-paired t test (two-tailed). *p < 0.05, **p < 0.01, and ***p < 0.001. d Methylation level of CCDC166 from genome-wide methylation sequencing was reversely correlated to Δ Ct values from qPCR-based methylation assay in 10 paired discovery samples. Pearson’s test was used