Dong et al. [16] reported the methylation of several genes, including RASSF1A, APC, homeobox A9 (HOXA9), GSTP1, blood vessel epicardial substance (BVES), and tissue inhibitor of metallopeptidase inhibitor 3 (TIMP3), in the tumor biopsies of 343 patients with HCC, but only the RASSF1A, HOXA9 and BVES gene promoters were hypermethylated in the serum of these patients [16]. The gene discussed is APC; the disease is hepatocellular carcinoma.