Background: Drug-metabolizing enzymes play a role in chemical carcinogenesis through enzymatic activation of procarcinogens to biologically reactive metabolites. The role of gene polymorphisms of several cytochrome P450 enzymes in digestive cancer risk has been extensively investigated. However, the drug-metabolizing enzymes with the broader substrate specificity, CYP3A4 and CYP3A5, have not been analyzed so far. This study aims to examine associations between common CYP3A4 and CYP3A5 polymorphisms and digestive cancer risk.
Methods: CYP3A4 and CYP3A5 genotypes were determined in 574 individuals including 178 patients with primary liver cancer, 82 patients with gastric cancer, 151 patients with colorectal cancer, and 163 healthy individuals.
Results: The variant allele frequencies for patients with liver cancer, gastric cancer, colorectal cancer and healthy controls, respectively, were: CYP3A4*1B, 4.8 % (95% C.I. 2.6-7.0), 3.7 % (0.8-6.6) 4.3% (2.0-6.6) and 4.3% (2.1-6.5); CYP3A5*3, 91.8 % (93.0-97.4), 95.7% (92.6-98.8), 91.7% (88.6-94.8) and 90.8% (87.7-93.9). The association between CYP3A4*1B and CYP3A5*3 variant alleles did not significantly differ among patients and controls. No differences in genotypes, allele frequencies, or association between variant alleles were observed with regard to gender, age at diagnosis, tumour site or stage.
Conclusion: Common polymorphisms on CYP3A4 and CYP3A5 genes do not modify the risk of developing digestive cancers in Western Europe.