In terms of early GC diagnosis, common tumor-driver gene mutations in cfDNA, such as HER2, EGFR, RAS, TP53, and epigenetic alternations detected by cfMeDIP-Seq, such as hMLH, CDH1, CDKN2A, H3K27, are sensitive target of tumorigenesis, which can be detected when clinical symptoms and imaging test are negative. The gene discussed is CDKN2A; the disease is neoplasm.