In our study, we found different methylation frequencies of the ten tumor-related genes in blood samples in GC vs controls (p16: 31.0% vs 2.0%, CDH1: 24.3% vs 0.9%, RUNX3: 63.2% vs 2.5%, MLH1: 19.5% vs 3.2%, RASSF1A: 61.5% vs 3.7%, p15: 43.0% vs 7.4%, APC: 50.6% vs 17.7%, GSTP1:10.8% vs 0.0%, Reprimo: 82.0% vs 11.0%, and MGMT: 40.9% vs 26.7%) (Supplementary Table 2). This evidence concerns the gene GSTP1 and neoplasm.