Karamitrousis et al. [105] used methylation-specific PCR to detect the methylation status of oncogenes RASSF1A, SOX17, and WiF-1 in the cfDNA of 70 patients with progressive GC and found that promoter methylation of the examined genes is significantly associated with decreased PFS and OS compared with patients without methylation and that simultaneous methylation of the above genes results in worse PFS and OS in GC patients. This evidence concerns the gene SOX17 and gastric cancer.