Abstract: Objective: To explore the association of cytochrome P450 1A1(CYP1A1 ) gene polymorphism and frequent risk factors of gastric cancer in Chinese Han people. Methods: One hundred and two patients with gastric cancer(GC), one hundred and ten with chronic atrophic gastritis(CAG), one hundred and three with chronic superficial gastritis(CSG), sixty-two with gastric ulcer（GC）, sixty-two with duodenal ulcer (DU) and sixty-two controls were enrolled in this study. Data on life-style had been routinely collected by means of common questionnaire sheets. CYP1A1 genotypes were detected by the polymerase chain reaction of sequence-specific primers (PCR-SSP). Hp infection was detected by an enzyme-linked immunosorbent assay (ELISA). The approach of case control was used in the analyses of risk factors. Results: Risks of gastric cancer was based on age, sex, education, occupation, helicobacter pylori infection, tobacco smoke, and CYP1A1 G/G genotype. Garlic had a protective effect on gastric cancer. Multivariate analyses indicated that risks of gastric cancer: helicobacter pylori infection, CYP1A1 G/G genotype, and garlic had a protective response. There was synergistic action between helicobacter pylori infection and CYP1A1 G/G genotype, tobacco smoke and CYP1A1 G/G genotype in the development of gastric cancer. Conclusion: An individual with a CYP1A1 G/G genotype is at risk of gastric cancer. This genotype may be considered as a marker related to the susceptibility to gastric cancer. It may provide a clue to define the risk of gastric cancer and lead to diagnosis and treatment at an early stage.

Key words: Stomach neoplasm, Susceptibility, Genotype