The effect of CYP1A1 and CYP1A2 polymorphisms on gastric cancer risk among different ethnicities: a systematic review and meta-analysis.

Potential Cytochrome P450s (CYPs) 1A1 MspI, 1A1 Ile462Val, 1A2*1 F, and/or 1A2*1C polymorphisms have been implicated in gastric cancer risk among different ethnicities. We aimed to explore the effect of CYP 1A1 MspI, 1A1 Ile462Val, 1A2*1 F, and/or 1A2*1C polymorphisms on the susceptibility to gastric cancer among different ethnicities through a systematic review and meta-analysis. Each initially included article was scored for quality appraisal. Desirable data were extracted and registered into databases. A number of 11 studies were ultimately eligible for the meta-analysis of CYP1A1 MspI polymorphism, eight studies for the meta-analysis of 1A1 Ile462Val polymorphism, and two studies for the meta-analysis of 1A2*1 F polymorphism. None of genetic model was evidently suggested, and thus all the genetic models were presented. Potential sources of heterogeneity were sought out via subgroup and sensitivity analyses, and publication biases were estimated. In our meta-analysis, significant results could be found in mutational heterozygous CT genotype, compared with wild TT genotype, among large sample size subgroup for CYP1A1 MspI polymorphism. Regarding CYP1A1 Ile462Val polymorphism, no statistically significant results could be found. For CYP1A2*1 F polymorphism, mutational heterozygous AC genotype, compared with wild-type AA, has deleterious effects, whereas mutational homozygous CC genotype, compared with mutational heterozygous type AC, has protective effects but lacks statistically significant difference despite its a proximity to 0.05. Combined mutational homozygous CC genotype and wild-type homozygous AA, compared with mutational heterozygous AC genotype, has protective effects. Our meta-analysis suggests no associations between CYP1A1 Ile462Val polymorphism and gastric cancer, but possible associations between CYP1A1 MspI and CYP1A2*1 F polymorphisms and gastric cancer, which needs to be further reinforced or refuted among different ethnicities in well-designed large-scale high-quality studies.