Garrigou and colleagues reported that hypermethylation of WIF1 (WNT inhibitory factor 1) and NPY (neuropeptide Y) was significantly higher in the tumor tissue compared to that in normal tissue and these methylated ctDNA (Met ctDNA) were detectable throughout the tumor progression, with their fraction being correlated to the tumor stage [70]. The gene discussed is NPY; the disease is neoplasm.