For instance, SEPT9 shows methylation positivity in plasma samples from CRC, GC, EC, HCC, and cervical cancers (Potter et al., 2014; Oussalah et al., 2018; Cao et al., 2020; Zhang et al., 2022; Bu et al., 2023), while P16 also serves as a common pan-cancer methylation marker (Hibi et al., 2001; Zou et al., 2002; Hou et al., 2005; Lou-Qian et al., 2013). The gene discussed is CDKN2A; the disease is hepatocellular carcinoma.