RESUMO
Objective: This study intended to explore the relationships of the polymorphism of phase II drug-metabolizing enzyme, microsomal epoxide hydrolase 1 (EPHX 1) with the habits of smoking and alcohol drinking, and their interactions on risk of deve-loping primary hepatocellular carcinoma (HCC). Methods: The genotypes at codon 113 of exon 3 of gene EPHX 1 were analyzed in 105 patients with HCC and 151 healthy controls in Guangxi Province by using polymerase chain reaction followed by restriction fragment length polymorphism (PCR-RFLP). The habits of smoking and alcohol drinking of all the subjects were investigated. Results: The frequencies of Tyr/Tyr, Tyr/His and His/His genotypes at codon 113 of exon 3 of gene EPHX 1 were 27.62%, 21.90%, and 50.48% for HCC patients and 21.19%, 34.44%, and 44.37% for healthy controls, respectively. There was no significant difference (P > 0.05). Smoking increased the risk of developing HCC for patients with His/His genotype. The OR value was 2.99 (95% CI: 1. 29-6.91). For the HBV-positive patients, polymorphism of EPHX 1 and the habits of smoking and alcohol drinking had synergistic effects on the development of HCC. Conclusion: The interaction between the environmental factors such as smoking and alcohol drinking and polymorphism of EPHX 1 gene may increase the risk of developing HCC.