Gastric carcinogenesis is a multi-factorial process that includes environmental, socioeconomic, and lifestyle factors. Many of risk factors, including dietary factors, chronic atrophic gastritis, intestinal metaplasia, and H. pylori infection, alcohol consumption, and aspirin have been investigated. Although the specific correlation between serum cholesterol and gastric cancer is not fully understood, inverse relationships have been observed between serum total cholesterol (TC) levels and cancer, and recent analyses of randomized controlled trials showed significant inverse associations between high density lipoprotein cholesterol (HDL-C) and low density lipoprotein cholesterol (LDL-C) and the risk of incident cancers. Lower lipoprotein cholesterol in cancer patients may be due to the enhanced activity of the lipoprotein cholesterol receptor pathway and to the increased demand for cholesterol during tumor development and lymphatic spread. Some suggested that the preexisting tumor might have resulted in low serum cholesterol, which is called "preclinical cancer effect" or "unsuspected sickness". In another study, LDL-C has been reported to affect host immune system cells.