Kushima et al successfully confirmed the instability and precancerous nature of PGA for the first time and confirmed the “pyloric adenoma-adenocarcinoma sequence” of PGA by comparative genomic hybridization (CGH) analysis, which showed that PGA shared genetic and phenotypic characteristics with gastric adenocarcinoma.[9] GNAS and KRAS mutations were also found to occur frequently in gastric PGA. This evidence concerns the gene KRAS and gastric adenocarcinoma.