Abstract: The initiation and development of gastric cancer is due to the effects from both external and internal factors. Recent researches show that external environment factors regulate and control the key genes expression during the process of cell’s growth and development through epigenetic modification such as DNA methylation or demethylation, histone modification and small RNA, thus playing an important role in gastric cancer’s occurrence and development.

Key words: Stomach neoplasms, Epigenesis, genetic, DNA methylation, Histone code, MicroRNAs